How to Make a Plastic Shell For a Robot Using a Soda Bottle and an Oven

By January 9, 2018Uncategorized

You do not need to have access to expensive vacuum molding equipment to make a professional looking plastic shell for a robot.

All you need is a large plastic soda bottle, a block of wood and your kitchen oven.

When a soda bottle gets hot it shrinks, so if you have a wooden mold inside it will shrink around it and form a shell.

For this technique to work properly your robot can not be any longer than the straight section of the soda bottle that you use.

Measure the length of your robot and then add two inches, one inch at least.

Now measure the bottle from where the curve at the top ends and the straight section starts down to where it finishes at the bottom.

If the bottle is big enough then you can start making the mold for the shell.

When you design the shape of your shell keep it as simple as possible, nice smooth curves are best.

You will need a block of timber the same length and width as your robot, the height of the block will depend on your shell design. Try to choose nice clear softwood such as a pine. Hardwood is too difficult to shape unless you have some serious woodworking equipment, whereas you can shape the softwood with a few hand tools and a lot less effort.

Once you have a wood block cut to the dimensions that you need, trace the outline of the shell onto the six sides of the block. The top view of the shell on the top of the block, the side view on the side, etc.

Cut the shape of the mold from the wood block and use a plane or chisel to remove any excess and then smooth the whole thing with sandpaper.

Remove the label from the soda bottle and rinse it out with water.

Cut the top off at the point where the straight section of the bottle ends, before it curves down to the cap.

Put your mold into the bottle and use some pieces of wood to wedge it in so it pushes tight against the bottle on the top and bottom of the mold, not the end of the bottle.

Now put the bottle, with the mold inside, onto a flat metal baking tray.

Heat up your oven to about 400 degrees and carefully put the tray in.

Watch it carefully and when the plastic gets hot enough it will start to shrink onto the wooden mold.

When it has finished shaving use some oven mitts to take the tray out of the oven.


After the plastic has cooled you can remove the mold and trim the excess plastic from the shell. Leave some extra at the bottom where the shell fits onto the robot to make it easier to attach to the base.

It may take a few attempts but if everything works as planned you now have a great looking molded shell for your robot. You can either leave it clear or paint the inside black for a great effect.

Source by Mark Geoghegan

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