Add conductive traces to vacuum formed plastic with 3D printing

Surface conductors on vacuum formed parts are featured in many hacks, from cosplay armor to 3D touchpads and smart objects. But making it has always been painful. Either they had to be hand painted after molding, which looked sloppy and laborious, or they had to be printed with a hard-to-use stretchable ink technology. [Freddie Hong] and his group have another solution, using technology most hackers already have: a 3D printer and a vacuum former.

plastic tray with electrodes to feel foil wrapped chocolatesSmart drawer made with this method.

They 3D print the tracks with conductive PLA filament directly onto a plastic base sheet and then vacuum mold the whole thing. The filament likes to deform when heated – it is printer filament.

We love this process. We have found that conductive filament is not reliably resistive across vertical layers, but it is reliable in the XY plane. Their method requires only one coat. They also suggest 3D printing a layer of non-conductive PLA on top of most of the conductor, such as a PCB solder mask.

Conductive filament has reasonable bulk resistance. They suggest electroplating it before applying the top mask layer. They are also exploring 3D printing of logos, stripes and the like with colored filament, or even creating surface details like rivets on model parts or adding thickness where the plastic thins out during vacuum forming.

To design the 3D print, you have to guess which piece of plastic film ends up where in the vacuum-formed last part. His group used a commercial program, t-sim, to make the prediction and Grasshopper to import the result into Rhino3D. This seems like a lot for a home hacker. Drawing lines on a test sheet and vacuum forming seems easier.

We’ve looked at vacuum forming before. We did a piece on 3D printing, and covered [Ted Brull]Kevo’s vacuum former back in 2015.

Thanks to [howielowe] for the tip.

This post Add conductive traces to vacuum formed plastic with 3D printing

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