Modular Laser Cut Tetris Shelves

This is an entry in the Instructables Remix Contest. DIY Tetris shelves is something that has been done before both with and without laser cutters. I wanted to add onto these designs though and work towards trying to make a laser cut-able Tetris shelf that is a fully modular design. Specifically, the shelves are not permanently stuck together, and can be rearranged into whatever pattern you want.

Tools and materials I used for this project:

Tools

• Laser Cutter
• Clamps (the more, the better)

Materials

• [$28 each] - 4x8 foot sheet of 1/4" thick plywood (you can make ~8 shelves)
• [$4 each] - 7 x 12 oz cans of spray paint (one for each Tetris block color)
• [$5] - 4 oz Glue, relatively quick drying (but not super fast)
• [$8] - 32 oz Wood stain
• [$18] - 32 oz Polycrylic finish
• [~$1 each] - 2 disposable brushes
• [$6] - Wide painters tape (at least 1.5-2 inches)

Make sure to get a formaldehyde free plywood (they like using that in the glue). Laser cutters + formaldehyde + your lungs don't mix well. I got mine in 4x8 foot sheets from Lowes for about $28, and cut them down to a size to fit into my laser cutter (by far the most economic option I found.

I made 2 shelves of every Tetris block, except for the square, which I made 3 of. I found that one can of spray paint ended up being just about perfect for coloring 2 shelves. The wood stain and finish is optional, considering that when stacked, you won't see most of the outside of the shelves anyways. But if you do use wood finish and stain, you will only use a small portion of the cans (I ended up using ~10-20% of each). So for a total cost estimate of the project:

• [$28 * 2 * 15/16 = $52.5] - I used most of 2 4x8 foot sheets of plywood
• [$4 * 7 = $28] - All of 7 cans of spray paint
• [$5] - All of 4 oz of super glue
• [$8 * 0.15 = $1.2] - Some wood stain
• [$18 * 0.15 = $2.7] - Some wood finish
• [$1 * 2 = $2] - 2 disposable brushes
• [$6 * 0.5 = $3] - About half a roll of painters tape

Total: About $95 total for the project, or $6.30 per shelf. Most of that cost comes from the plywood and spray paint.

I designed the shelves using Autodesk Inventor, taking advantage of parameters to define my the shelves using just 5 dimensions (the width of the shelves, how deep the shelves will be, how thick the plywood is, and two dimensions for the length of each individual box joint segment). I designed it this way because I was still deciding on the dimensions that I wanted the shelves to be, and this allowed me to modify just these dimensions to change all of the shelves. In the end I decided on shelves that were 6 inches wide and deep, which I thought a good length for 1/4 inch plywood.

To make them truly modular, I wanted a way to be able to connect the shelves that wouldn't be permanent or very bulky/obvious. In the end, I decided to test a solution that involved having a small slot at each of the back corners of the shelves that can be zip tied together. This solution had some advantages and disadvantages that I will discuss at the end. If you don't want the small slots because you plan on gluing the shelves together, or want to use a different method, it should be a simple fix to remove them from the laser cutting file.

There are 13 unique pieces total, 7 of which are the back panels of each shelf, and the remaining six are the sides of the shelves. The first two lengths (6 and 12 inches), also have an extended varient that is 0.22 inches longer (the thickness of the plywood). Any piece which (for lack a better phrase) "wraps" back inward on itself, requires at least two of the extended pieces.

The attached file has only the 13 unique pieces, so in order to make each shelf, along with the back panel you will need:

• Straight (light blue) - 2 single unit, 2 quadruple unit length pieces
• Inverse L (dark blue) - 2 single unit, 1 extended single unit, 1 double unit, 1 extended double unit, and 1 triple unit length piece
• L (orange) - Same as Inverse L
• Square (yellow) - 4 double unit length pieces
• Inverse Skew (green) - 2 single unit, 4 extended single unit, and 2 double unit length pieces
• Skew (red) - Same as Inverse Skew
• T (purple) - 3 single unit, 4 extended single unit, and 1 triple unit piece

If what listed above is a little confusing, look at the attached graphic I included in this step (last pic). It shows each block, where the blue lines represent a single unit length (6 in), the red lines represent normal length sides, and the green lines represent the extended length sides.

Because I used 1/4 inch plywood, I recommend using a laser cutter that is at least 40-50 Watts. The laser cutter I used is 50 Watts, and 1/4 inch plywood is close to the limit of it's cutting ability. After the laser cutting, I used a safety knife to finish cutting any parts that didn't quite cut through.

The main reason I say that this is optional is because most of the sides will not be visible when the shelves are together, and it is quite a bit of work to stain all of the sides when only a small amount will be seen at a time. But in an effort to keep it fully modular, I went ahead and did the staining.

To make sure that I was staining the correct sides, I assembled each of the shelves (without gluing them), and marked the inside (that will be spray painted). For the staining, I used a single coat of a dark wood stain.

The most important step! It's the most important because when gluing you want to make sure that the shelves are as straight as possible since you want to be able to fit them together with essentially no gaps between. Gaps could be created by pieces that are inherently warped, or by poorly assembling the pieces together. The simplest way I found to mitigate the misalignment issue is by clamping the piece together while the glue sets. Because I needed to get through 15 shelves, I wanted to use a glue that had a clamp time that wasn't too long (like regular wood glue, which is ~30 minutes), but didn't rush me when assembling the shelves (like the fastest super glue, which bonds in ~10 seconds). The glue I found with just about in the sweet spot had a clamp time of 3 minutes. This was enough time for me to be able to apply glue to all of the joints, assemble the shelf, and clamp it together before it set.

Next up, for the spray painting I carefully started by outlining the front with a layer of painter's tape to protect the stained surface from getting hit. Don't forget to also tape over the slots at the bottom (where the zip ties will go through), and make sure that the tape is a snug fit. I had a couple shelves where the spray paint still bled through a bit along the tape.

Number of applications varied between the colors, but it ended up taking ~4 layers of spray paint to fully color each of the shelves. As mentioned, I found that one spray can is good for just a bit more than 2 shelves.

The last step in assembling the shelves is adding a finish to the outside. Again, optional since these sides will mostly not be seen, but still nice to do to make them truly modular. I added a single coat of polycrylic wood finish to all of the stained sides.

Having a bunch of shelves stacked on top of one another without anything actually attaching them is an easy way to turn your game of Tetris into the very end of a game of Jenga. The simplest (and most permanent) solution is to glue the shelves together in the final configuration that you want. I wanted to avoid this so the solution I tried was including little holes at the back corner of each shelf that can be used to zip tie the shelves together. The key advantages to this is that it is very minimal and hard to see, and ended up doing a pretty good job securing the shelves together where they fit. The main disadvantage is that they only secure the back of the shelves together (meaning they are free to bend away at the front), and they don't work at places where one shelf doesn't have a corner. Overall though, I was pleasantly happy with how well and hidden the simple zip tie method turned out, and would recommend it to anyone looking to do this project as well.

Depending how high you stack them, I would also definitely recommend securing the shelf to the wall it is leaning against, so that it doesn't fall over.

And that's it! You now have a set of Tetris shelves that can be mixed and matched to any amount of orientations. I hope you enjoyed this Instructable.