Bare Bones Vacuum Forming Box

First of all, this Instructable was made to supplement the original video for the project, as it is more of a "watch me make this thing" kind of video. If you're following my instructions to make your own vacuum forming box, make sure to use the video as visual reference.

You've made a really cool thing and you want to share it with the world, but how do you do it? You could make a silicone mold and cast resin copies, but that entire process is pretty messy and expensive. Why not just make another copy the exact same way you made the original? If you're anything like me, you already spent weeks perfecting the original and the thought of doing all of that over again is pure nightmare fuel. What's a maker to do?

If you read the title then you'd know that we're going to utilize the power of vacuum forming!

Vacuum forming is the process with which you can make cheap lightweight copies of of your original 'thing' out of plastic, not unlike the plastic lids you use for your cups as fast food establishments. There's nothing too difficult or scary about this project if you're already into the whole making and DIY scene, so let's get into it.

Keeping with the 'bare bones' theme, the entire project was completed with tools and materials I already had lying around the shop.

- 1/2" Plywood - You can actually get away with 1/4" at this scale, but any larger you'll want to keep it at 1/2" or 3/4". You don't want your box to collapse on itself.

- 1/4" MDF - This is used to make the raised top of our box, as well as the frames that hold the sheets of plastic when forming.

- Various screws and wood glue - You can complete this project with screws or glue alone, just as long as the sides of your box are air-tight. It's best to use a combination of the two.

- Table saw or miter saw - Obviously for the woodworking aspect of the project. You can pretty much use any saw you have access to. Hand saw, band saw, jig saw, etc.

- Drill or drill press - A drill press makes drilling all of the tiny holes in the top of the box much easier, but a regular hand drill works just fine.

- Shop vac - This will be our vacuum source. It doesn't have to be too hefty to get the job done. Mine is a cheap $30 model that you can get at any big box store.

- Toaster oven - This will be our heat source. If you don't already have one, this will probably end up being the most expensive part of your project. My oven is for shop use only, but I have seen others use the ovens in their kitchens. Keep in mind that we will be heating plastic, so use your best judgment.

- Plastic sheets - This is the material that will eventually become our vacuum formed part. In this case, I used .06" white styrene sheets that I purchased from Amazon.

- Thick gloves - This particular setup is very hands-on, meaning you'll be handling hot materials, so you need gloves that will protect your hands from the heat.

While the process remains virtually the same no matter what you're forming, there are a couple different vacuum and heating elements that can be utilized.. We're going to be using the most basic setup for both.

First of all, we're going to make our vacuum forming box. At it's core, our setup is literally just a box with lots of tiny holes in the top and one large hole in the side. The large hole in the side is where our shop vac is going to attach, while the top of the box is where all of the magic will happen.

Before we begin, you need to determine what size you want to make your box. A good rule is to take the widest portion of the thing you're making copies of and add a couple inches to it. This gives your plastic sheet enough space around the part when it's forming to fully conform to your part before the plastic cools.

After you've determined the size, you need to start cutting your parts. The parts breakdown goes like this -

- A top and bottom of equal size made from plywood

- Four sides of equal size made from plywood

- One riser layer an inch or so smaller than the top of your box

After you've cut all of your parts, assemble the sides, top, and bottom using wood glue. I just used simple butt joints on all of the pieces because it was quick and easy. When everything is glued up, these joints are more than sturdy enough to withstand the force of the vacuum. To cut down on waiting time, I used my brad nailer to hold the pieces together while they dried so I could move on to the other steps of the project. You could also use screws, but be sure to pre-drill your holes to avoid splitting the wood.

Once the box is assembled, center your MDF riser on the top and glue it in place.

Next, lay out a grid of 1/2" squares on the MDF riser. This will be the guide for drilling your holes. Depending on the size of your box, you may need to adjust the size and spacing of your holes. The drill bit I used was 1/8", but smaller holes are better, so I'd aim for 1/16" or smaller.

The next step after drilling the holes in the top of your box is to drill the hole in the side for the hose on your shop vac. You want the hose to fit snugly in the hole, so trace the end of your hose onto one of the sides of your box and drill lots of holes inside the perimeter of the circle. Knock out the center and smooth down the sides of the hole with a file or coarse sandpaper. If you have a forstner bit or a hole saw that is the exact diameter of your vacuum hose, this step goes a lot faster.

The last step is to hook up your vacuum and turn it on. If you can feel air being pulled through the holes in the top of your box, that means it works! You can also use various flat materials, such as plywood or your plastic sheets, to test the suction of your box. If it seems a bit weak, make sure that all of your joints are air tight.

The next part we need to build is the frame that will hold our plastic sheet while it's being heated and formed. Ideally this would be made from aluminum, but we'll be using 1/4" MDF because that's what was readily available.

The frame is really straight-forward. You want to cut two pieces of MDF that are the same size, or slightly bigger, than the top of your box. Not the MDF riser, but the 1/2" plywood top. Trace a square slightly bigger than the raised MDF riser on the center of your two pieces. It's critical that this frame be able to easily slip around the riser so that you get a good seal between the plastic and the box.

In the video, you'll see that my first attempt at cutting out the inside of the frame was a disaster. The MDF couldn't handle the force of the jigsaw and broke apart. If you have a scroll saw or a coping saw, you'll easily be able to cut the center out with no fear of destroying the frame. A jigsaw will probably work if you have a smaller blade.

Alternatively, you can use the second method that I tried in the video and cut strips of MDF and butt the ends together to form your frame. In the long run, this won't be as sturdy as a solid piece, but it does get the job done.

When it comes to clamping your plastic sheet between the two frame pieces, you have a couple options. The way that I went about was just to drill and countersink holes all along the frame for screws. The screws go through the first half of the frame, through the plastic sheet, and finally through the second half of the frame, clamping everything tightly. An alternative method is to just use binder clips all around the edges of your frame. They're cheap, easy to apply and remove, and will withstand the heat of your oven.

Once you've finished your box and your frame, you're ready to go! I should say that whatever you're trying to make copies of should be able to support itself under vacuum and be able to withstand the heat of the plastic. MDF, solid wood, tooling foam, resin, and plaster are all common materials that people use for their masters. You want something solid. Things like EVA foam and clay aren't very good materials to use with vacuum forming because they will warp and distort with the heat and pressure, rendering your part useless.

Throw on your gloves and preheat your oven because it's time to vacuum form something! Make sure that your plastic is tightly secured in your frame and put it in your oven. Start at a low temperature, around 250 - 300 and don't take your eyes off of the plastic. Once it starts to heat up, you'll see the surface start to ripple. After a couple seconds of that, it will smooth back out and start to sag in the middle. Quickly remove the frame from the oven and give the bottom of the soft plastic a tap. If it's floppy enough to slump back to it's saggy shape, you're ready to go. If it takes a second for it to slump back down, put it back in the oven for a few more seconds. Note the soft look of the first attempt in the pictures. This happened because the plastic wasn't hot enough.

Here comes the part where I tell you that the process is just a lot of experimenting with your oven. It's not really an exact science. It depends on the size of your oven, how close the plastic is sitting from the heating elements, etc. The main thing is to start slow. If you heat your plastic too fast, the surface finish of the formed part will come out bumpy, kind of like the orange peel effect from a bad spray paint job.

Once you feel that the plastic is ready to go, take it out of the oven and place it over your master, making sure to press it as firmly as possible so you get a good seal. You only have a few seconds before it's starts cooling to the point where all of your details will become soft, so quickly turn on your vacuum. If everything was done right, you should see that plastic be sucked down onto your master. You have another couple seconds at this point to use your fingers to manipulate any areas that didn't quite get suck all the way down. Leave your vacuum on for a few more seconds and you're done.

Once your plastic is cool, you can remove it from the frame. More often than not, your master will be stuck in the newly formed part. Wiggly the plastic until your part pops out. You can make this process easier by making sure your master doesn't have any undercuts, as the plastic will encase it, meaning you'll have to cut it out. Sprinkling some talcum powder on your master before vacuum forming will also help.

Congratulations! You just made your very first vacuum formed part! It may take a while to get the hang of it, which is normal, but the great part about this process is that the materials are fairly cheap and readily available. If you have a local hobby shop or a sign shop, they probably already have all of the plastic you could ever need.

This process is perfect for cosplayers that want to make armor without breaking the bank. It's also great for artists that want to make fancy packaging for their products, such as blister cards for action figures or shipping containers for vinyl figures.

Feel free to leave any questions you may have in the comments below and I'll do my best to answer them!