A couple of days ago I had an idea. Do you think it would be possible to design and 3D-print molds from Shapeways or other companies to cast puzzle pieces out of resin? Would it work with WSF? I know they wouldn't work very well as is but it's definitely possible to smoothen them out with sandpaper or ABS solvent. Would they be cheaper than silicon rubber molds? Would they be more or less effective? What do you think?

I'm certainly no expert, but I'm sure printed ABS would work better.

The biggest problem is that the resin would seep into the pores of WSF or adhere to plastic in general. The second biggest problem is that plastic (usually) isn't flexible enough to work as well as silicone.

I agree: A mold needs to be smooth for the part to come cleanly out, and for most designs needs to be flexible to allow it to remove easily.

The work to smooth a mold is probably more than the work to smooth a printed part and make a silicon mold from it. Sanding small interior spaces is really hard, but sanding small exterior features quite possible.

Dave

I had an idea a long time ago on how to make the printing and molding process easier, but never carried it out.

The idea goes something like this:
Design and print "master plates" for casting the two mold halves. The plates will be the "positive" for the "negative" silicone molds. Once you have the plates designed, all you need to do to make a new mold is to place the plate in the bottom of a small box (to bound the sides of the mold), then pour in the silicone for both halves at the same time. When the mold is set, remove the bounding box and master plate. The two sides should fit together quite well as long as the plates are designed properly, and there are no flaws in the print.

The big advantage in this is that you can make both halves of the old at the same time, and then when the first molds wore out, you can make a new set the same as the first! This would speed up the short run production cycle as it would reduce re-work to make new molds from master parts.

Some disadvantages are that the plates require more design work and print cost, but that can be offset by the time saved in making the molds. The material would need to be a high detail material for a good mold (added cost).


It is an interesting idea... Any thoughts?

Would printing in the metal material the seal off the pours in the material.

Definitely, but I could only imagine how much that would cost...

Wow, I actually never thought of that! I'm just wondering how to prevent the molds from gluing shut. Would the plate prevent the two halves of the mold from touching?

You would need a plate for each side of the mold. In effect, the plate forms the entire touching faces of the mold, and leaves a cavity in each side. When the two poured silicone halves are combined, the mold cavity is formed.

The plate could also be in the form of a cup, ready to pour in silicone and make a mold.

In theory this will work great, but keep in mind that items like keyed bumps need to be designed into the mold plates so that the mold halves go together properly.

See pictures below for an example of mold plates for a simple extended 3x3x3 edge.