Introduction: Making Vacuum Former for £2 Out of Scrap Material Using 3D Printed Molds

This guide will show you how to make a A4 sized vacuum former using bits of scrap materials that you might have lying around at home. I was suprised how quick and easy it was to get great results!

If you're not too familiar with vacuum forming, it is a very easy way to mold plastic over one side of a mold. Some examples of common things made using vacuum forming are:

  • old plastic sandwich boxes
  • chocolate box trays
  • cutlery seperators
  • plastic cover of a bike helmet
  • packaging (blister packs)

Note: This design works for A4 sized plastic, not A4 sized molds

WARNING: Be careful to choose a plastic that will not product toxic fumes.

Remeber: To design every face of your mold with at least a 4 degree angle to allow easy removal of the mold (note; I didn't do that with the holes in the side)

Even with a 3D printed mold it took the shape very nicely but I did suffer a bit of heat warp in the PLA printed part, next time I will try putting it in the freezer first or using a higher meld 3D printer filiment (PETG or ABS).


Materials you will need (see pic):

  • Something to make a box out of. I used scraps of 10mm MDF with PVA glue and nails but in hind sight I might have used a plastic food box to save time
  • Something to make a frame from. I used some scraps of 2mm aluminium
  • 12 bulldog stationary clips for holding the plastic onto the frame (the only thing I bought, costed £2)
  • A vacuum cleaner
  • Some plastic for vacuum forming. I used PETG, polystyrene is another cheap vacuum forming material.

Tools you will need are:

  • Wood saw (not needed if you use the plastic food box instead of the MDF)
  • Drill
  • Step drill bit
  • Angle grinder
  • Ruler/tape measure
  • Set square
  • Sanding mask
  • Ear defenders
  • Goggles

For doing the vac forming you will also need:

  • A heat source. A kitchen grill works perfect! It's the same type of heat source that industrial vac formers often use
  • Sissors
  • Oven gloves

Step 1: Design Your Mold

Design your mold in CAD ready for 3D printing. Of course you can make a mold using other methods too, e.g. layers of MDF glued together then cut down by hand or CNC machine, or you can just have fun vac forming objects around the house for almost endless fun!

I desiged a part to protect a soft things from wear in a ventilator:

I would reccomend placing your mold in the freezer for a few hours before using it as my mold got a little warped from the heat and the cold will speed up the cool down

Step 2: Make the Vacuum Base Box

I used a sheet of 10mm MDF that I had lying around but you can use whatever sheet you have, OR just find a plastic food box to save loads of time (wish I had thought of that before).

My MDF box's outer dimensions are: L:220mm x W:130mm x T:58mm

The length and width were chosen to give clearance for the frame. The thickness was chosen to give room for the hose from my vacuum clearner to attach


  1. Measure and cut all panels to make the box size of your choice (remember: measure once, cut twice). I would reccomend drilling the hole for your vaccum cleaner hose before cutting out the panels, the step drill bit worked great for this as I could stop slightly short to leave a bit of material at the next hole size down for a very tight fit on the vacuum hose
  2. Drill holes in one of the large panels for the air to flow. I use 3mm holes spaced about 10-20mm apart. (remember to leave a boarder around the edge without holes for the mating face with the side panels)
  3. Line the edges of your panels with PVA glue and carefully place them together and use the nails as well. try to make a continous bead of PVA to seal the faces from air leaks
  4. Sand down box

Step 3: Seal MDF Box

Look for any air gaps in your box and seal with glue PVA will work fine but will take hours to dry. I used super glue with activator.

Then run a leak test with your vacuum cleaner attached, feel with your hands around the box for leaks. If it's sealed well you will only feel leak around the holes that you drilled

Step 4: Make Your Frame

  1. I marked out the size of my frame on the 3mm aluminium based on the A4 sheets of PETG that I had. The outer perimeter of the frame is A4 sized and the inner perimeter is 25mm (1") offset
  2. Cut out the frame with an angle grinder with cutting disc. Use all the PPE, honestly it's needed! Probably a good idea to wear gloves as well

Step 5: Get Forming!

  1. First attach your A4 plastic to your frame using the bulldog clips
  2. Press your vacuum cleaner nozzel into the hole in your box
  3. Take your mold out of the freezer and place it in the middle of your vacuum box. Make sure that there are holes all the way around the mold
  4. Pre-heat your grill
  5. Once once the grill is up to temperature, place your vac box with part on top in the floor of the grill and at the same time hold the fram with plastic just below the heating element. Use oven gloves!
  6. Watch the plastic as the gets hot. You're looking for the plastic to bow a bit but not too much, it only took me about 20 seconds with a pre-heated grill
  7. Once the plastic is ready (try and do these things quickly):
    1. lower the plastic with frame onto the part
    2. switch on the vacuum
    3. and remove everything from under the heat

Watch the video below to witness my second attempt. On my first go I left the plastic for too long under the heat and it bowed way too much which caused the plastic the crinkle on the mold

Step 6: Release Mold

It should either just fall out, or take a couple of taps. Mine took a bit more persuasion because I left holes in my mold that the plastic gripped onto. Remember: always make every face at least 4 degrees for easy mold release. No vertical faces or overhangs

Step 7: Trim Part

Use sissors to trim the unwanted bits from your molded part

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