Cardboard Marble Roller Coaster

In this instructable, I will show you how to make a hand-powered marble roller coaster, made of cardboard!

It has two paths which the marbles can follow, which recombine at the end, then the marbles enter a wheel which lifts them back, and they choose one of the two paths again. (Note that in my roller coaster, the marbles sometimes stop in one of the tracks).

I have provided easy-to-follow instructions with PDF templates for the more complex parts (you will have to draw out the simpler ones though!).

I have made such rollers in the past and studied some clever designs, and I thought that the Stick It! Contest was an excellent opportunity to try my hand at it.

To make this instructable, you will need :

• Cardboard
• A glue gun (with sticks)
• Paper glue
• Paper
• Pens
• Pen refills
• A pair of scissors
• A cardboard cutting knife
• Sandpaper
• Marbles
• Aluminium foil
• Cellotape
• A stapler
• A hammer (with nails)
• Weights (small stones, broken crockery etc.)
• A plastic dispensable bottle
• A printer (for printing)
• A cardboard tube (replaceable)

Note that not all of these materials are in the photo above.

Attached below are the PDF files you will need. They are meant to be pasted on cardboard, and then cut out. They must be printed with their actual size on landscape orientation.

You can cut them all out now, or wait until the right step. Here, you will need the 'Base layout' file. Print, paste and cut it out. The base is designed to fit on an A4 paper, so all the printed paper should be used.

Remember to wait for the glue to dry before cutting!

The base indicates the guidlines for gluing on the bottom pieces, after you are done, every single line should be covered.

After cutting out a cardboard part, I prefer to sand down it's edges. It is very effective in smoothing out the contour.

In this step, you will make most of the walls required for the first path.

Print out the 'Wheel guard & wall 1' file. The wheel guard is the circular part, which will be used much later. Paste and cut out the other part (remember to sand it!). Push (or hammer) a hole through the circle, it should be wide enough to allow a pen refill to be pushed through.

Refer to the images for the exact position, and glue it on the base. The dotted lines tell you some necessary information on where to paste cardboard pieces.

The base is designed for single-corrugated cardboard, as I had only triple-corrugated cardboard at hand (worst case), I had to often deviate from the exact design, and made some small mistakes. The measurements noted here are for single-corrugated cardboard ONLY, but I still recommend that after you know what a piece does and where it goes, take your own measurements to remove individual variations and errors.

Most of the walls are going to be simple right-angled trapezoids. For the first part, cut out trapezoids of dimensions:

1. Base - 10cm, heights - 16cm & 14.5cm
2. Base - 8cm, heights - 16cm & 14.8cm

Draw lines parallel to their sloped sides and 1cm from them. On the wider one, draw a vertical line 2cm from the longer side. Cut out the small piece where the lines intersect. Look at pictures. Glue them down on the right guidelines. The longer one is to the right in the picture.

Cut out further pairs of trapezoids of dimensions :

1. Base - 10cm, heights - 14cm & 13cm
2. Base - 6cm, heights - 13.8cm & 13.2cm

and,

1. Base - 4cm, heights - 11cm & 11.7cm
2. Base - 3cm, heights - 11.1cm & 11.7cm

Draw a line 1cm down from their slopes too, and paste them. Look at pictures.

NOTE : Draw the "1cm line" on each piece on what will be the inside of the track. Look at pictures from later steps for details.

Cut out a piece of cardboard 13.5cm X 1.8cm, again, the dimensions are for thin single-corrugated cardboard only, anything else will have to be significantly trimmed.

Hold the piece as shown and make slight marks where it is not bordered by any cardboard. They should be about 1.8cm apart.

Cut two small pieces as wide as your marks and 2cm long.

Cut off two triangles at 45 degree angles at the ends of the strip. The cutout shape is meant to snugly fit in with other pieces of the track.

Glue the two small pieces between your marks.

Finally, glue the strip in it's position. Make sure that it runs along the lines you drew earlier.

Here, you will make the last walls required for the first path.

Cut out a trapezoid of dimensions :

Base - 6cm, heights - 14.5cm & 14cm

and a smaller rectangle of 2cm X 2.5cm, look at further pictures to see where this will go, and skim off 'by-eye' a small triangle off it's top.

Place the large trapezoid as shown, and make small marks on the outer side. Extend these marks up 12cm and join to from a rectangle, cut this off.

Paste both pieces as shown.

Cut out rectangles of dimensions :

1. 3.8cm X 1.8cm
2. 9.8cm X 1.8cm
3. 5.8cm X 1.8cm
4. 9.8cm X 1.8cm

(One measurement is repeated.) Taken in order, these rectangles constitute the track in ascending order (quite literally). Cut off triangles with 45 degree angles from their sides as shown in pictures, and paste them.

Make sure that the track runs along the lines you drew earlier.

Print, paste and cut out the 'Walls 2 & 3' file.

Take the slightly longer of the two walls and paste it on the base, look at pictures for the right guideline.

Cut out three rectangles of dimensions :

1. 2cm X 10cm
2. 2cm X 5cm
3. 2cm X 20cm

'Sharpen' one end of the longest rectangle. Glue them down on the dashed lines as shown.

Glue the other piece on the track pieces such that both the walls are aligned. The holes on the walls should be level.

The splitter is meant to divide the marbles equally between the two possible paths. A marble rolling off the right track would set it up for the next one to go to the left, and vice-versa.

Cut out a rectangle 16cm X 1.8cm and punch a hole on it at 5mm from the top. Glue it as shown.

Cut another piece of 3cm X 2cm, which will be the 'floor', and glue it as shown.

Cut three pieces of dimensions :

1. 1cm X 1.5cm
2. 4cm X 1.5cm
3. 3.5cm X 1cm

Assemble them as shown. I ripped thin pieces of my cardboard for this, but it turned out to be a mistake, as the middle piece needs to be quite thick. I ended up replacing it with two triple-collated pieces. The dimensions were also slightly short, and I have corrected them here.

Cut out a piece of refill 4.5cm long and it's pen casing 1cm long. Glue the pen casing on the piece you made as shown. Remeber to sand the cut smooth.

Thread the refill through the holes in the cardboard and the pen casing, and glue it down.

Test it and make any corrections required.

The 'pump' is meant to transfer marbles to a lower track from a higher one. The marbles fall in it, upon which it lowers, the marble rolls off and it snaps up.

Cut 3 pieces of 8cm X 1.5cm and 1 piece of 6.5cm X 1.5cm. On 2 of the longer pieces, cut off a triangle at 45 degrees and make a hole at 3cm from the flat end. The holes should allow easy passage of a refill.

Assemble the longer pieces as shown and glue a 1.5cm X 1.5cm square just before where the cut ends. Glue the smaller piece for the roof.

Thread the refill through the holes in the wall and the pump, and glue two 2cm X 3cm pieces at each end to hold the refill in. There is no need to glue the refill to anything. Put a 2cm X 2cm piece to keep the supports stable just beneath the pump as shown.

Put a dab of glue on the refill to align the pump with the track (may be unnecessary).

Put some counterweight (I used broken pottery) in the open end and seal it off.

Take a 5cm X 1.5cm piece and stick it as shown. The marbles will only be able to proceed when it is lifted! But a marble may push it open by itself, so put some glue on the track right before the block to slow down the incoming marbles.

The 'catch' is meant to catch marbles falling off from where the track ends in the second path.

Cut out a 17cm X 7cm piece and strip it to make it bendy.

Stick it along the circular guidelines as shown.

Glue two 6.5cm X 1cm pieces to connect it to the opening in the wall.

Cut out a 2.7cm radius circle and glue it inside. Be careful to make a slight slope towards the opening!

Use a small trapezoid piece to fill the remaining gap. Approximate it's size. Make sure the marbles can't stop anywhere and correct if they do.

Cut out a 5cm X 5cm square and glue it along the guidelines as shown.

Then cut out a trapezoid of base 20cm and height 4.5cm and 3cm. Glue it as shown.

Cut out two smaller trapezoids of base1.5cm and heights 3cm and 2cm, and glue them along the last guidelines.

Cut out a rectangle of 5cm X 2cm and make a 45 degree cut along on of it's ends. Make a similar cut on the other side such that it meets the first cut on the other side. Glue it along the track as shown. Be careful to make sure the slope exists. Cut out a rectangle of 22cm X 3cm, cut off a triangle at one of it's ends and score it 1.5cm from the other and bend down the scored part. Glue it as shown.

Important : Make sure that where the track ends it is exactly 1cm off the ground.

The lifting wheel is the most complex part of the assembly. It requires quite a bit of delicacy to make. Each cubical 'hatch' a marble goes into has three relevant sides; the floor sloping inwards, and the roof and one wall sloping outwards.

Cut out the wheel guard file and glue it on the guidelines as shown. Then cut out two circles of radii 10.5cm and make holes in their centers that can snugly fit your pen. Draw two circles of radii 9.5cm and 7.5 cm. Using these, draw and cut out 4 equally spaced squares of 2cm X 2cm (3 might also work). These cuts need to be quite good.

Cut out a 1.5cm cardboard tube of radius anywhere from 2cm to 6cm and use it to glue the two circles together as shown.

Now comes the delicate part: cut out a square of 1.5cm X 2cm and glue it on the outer edge of a square such that it has an inward slope when it's cut square is held vertically downwards. Do the same for the inner edge, only it must have an outward slope when it is held vertically upwards. Look at pictures for a better idea.

Next, cut out a similar piece and trim it's edges about 2mm to make it a parallelogram. This is meant to go between the previous two pieces. Glue it on the right wall (when the cut square is vertically down) with an outward slope. Hold the wheel vertical with the cut square to the left to make sure of the slope.

Cover the last wall with anything you want, ideally, it won't be used at all.

Repeat for remaining three squares. By now you should be able to test the wheel by holding up a pen in the wheel and going through the wheel guard hole. Throughly test each hatch. I used cellotape and hot glue for a quick slope correction on the track near the wheel.

Cover up the inside of the wheel with paper.

Next, draw a 7cm radius circle on the other side of the wheel. Cut out and strip a 44cm X 1.3cm long cardboard piece and glue it along the circle.

Cut out a 10cm piece of pen casing (sand the edges!) and glue it to the wheel. Use glue only on the side shown. There should be about 2cm of it on the other side. I had to extend mine later as it was too short.

Cut out an 8cm radius circle and glue it on the stripped cardboard. The wheel is complete!

Cut out a trapezoid of base 20cm and heights 14cm and 9cm. Cut out a hole 11cm up and 2.5cm from the taller side and another 8cm up and 1.5cm from the smaller side. Make sure your pen turns freely through them.

Thread the lifting wheel through the wheel guard and the trapezoid's holes and glue down the support along the longer guideline. It will overshoot the end of the guideline. Mine appears to be displaced due to the thickness of my cardboard. It doesn't matter if it rubs against the wheel - a bit of friction never hurts.

Cut out two strips of 1.8cm X 10cm. I had cut them 17cm long, but that is not needed since they don't have to touch the floor. Glue them between the wheel guard's opening and the splitter as shown, they don't need to go all the way down. Cut out a small rectangle and stick it between the recently stuck strips. Due to an earlier mistake, I had to make some more corrections, but you won't have to.

Cut out two circles of radii 4cm, draw a 3cm circle on one of them. Make sure their central holes snugly accomodate your pen. Cut and strip a 19cm X 1.3cm piece and glue it along the drawn circle. Cut a piece of pen casing 7cm long and glue it to the wheel as shown, use glue only on the side shown. The pen should protrude ~1.5cm on the other side. Glue the other circle to the stripped cardboard to finish the driving wheel.

Cut a 10cm X 4cm piece and make a large hole 8cm up on it. Thread the driving wheel through the hole in the trapezoid and this one and glue it on the final guideline. Cut a piece of 2.5cm X 4cm and glue it as shown for support. Cut a piece of 8cm X 1.5cm and glue it between the driving and lifting wheels, but make sure it touches neither.

Cut a rectangle of 3cm X 7cm and make a hole 1.5cm from either side.

Glue a 6cm long pen casing to one of them make sure it does not protrude much on the other side.

Thoroughly glue the other hole to the pen sticking out of the trapezoid. Make sure this bond is tight as it will transfer all of the required torque.

The belt will be made from compressed aluminium foil, which is much more stronger than it sounds.

Cut out a sheet of aluminium 35 cm long, it helps if it's also about 30 cm wide. Cut it length-wise to get two smaller sheets.

Fold one sheet over 4 times and hammer it thin. Then throughly cover it with cellotape - literally, worship it with cellotape! Cover every edge and corner.

Repeat for the other one and then staple the two together. Cover the staple with cellotape too.

Then thread it under the two wheels, over it's tracks and staple the two ends. Cover this with cellotape too. Make sure the belt is tight - but not too much.

And finally, It is Done!!!