Yes, you can 3D print a mold and we release this design tool: https://cad.onshape.com/documents/f3ec62110b01a3ad0fcb6d85/w...
You can make whatever 2D shape you want in shape_sketch, as long as it is within the bounding square, and we automatically generate molds with the requisite inlet and outlet channels! It is still in prototype mode and we are working to make it robust, but it generally works and was used to make all the different shapes you see on the website and in the paper.
As for what it is sensing, we learn end to end policies in this case, and allow the neural network can pick up on whatever it needs for the particular task! but we have run experiments with a predecessor of AnySkin, ReSkin: https://reskin.dev that indicate you can localize contact at sub-mm scale as well as sense normal and shear forces!
https://formlabs.com/blog/inside-production-robot-hand/ is from almost a decade ago, but yeah - print a mold, stick electronics in slots in the mold, pump silicone around it. Back then it was sort of novel that commercial-grade resin printers could produce smooth enough surfaces for this; I expect that today, hobbyist-grade ones probably suffice.
there are a lot of magnetic-particle FDM materials out there, I guess a project like this is waiting for a filament house that wants to start experimenting with magnetic powders + TPU.