So it's been about 24 hours since I poured the Smooth-On "Dragon Skin" platinum cure silicone to pot the electronics for one of the milklichts...and I have a lesson to report:

*Don't* use gaffer tape as a mold enclosure! The silicone at the very edges of the piece appears to be fouled and will not, I fear, ever cure. This has happened to me a couple of times in the past, but I've never had the wisdom to reflect on exactly which part of the process was at fault (I'm also guilty of habitually trying to use years-old silicones, because I begrudge throwing out unused raw materials).

I was able to rescue the piece in a pretty ugly, but usable way: I got a very sharp hobby blade and carefully cut away the outer ~2mm of each side, exposing a fully-cured area underneath.

The downside to the silicone-potting approach (even if the edges _had_ cured properly) is that it more or less guarantees that the user will pick at it. If I had milled a mold into which I cast the silicone, I'd avoid rough/imperfect interface between silicone and wood, but that would have required a lot more time and planning and a lot less beer...