Yeah, it dawned on me after a bit how infeasible that would be. At best I was thinking little static cling stickers for the dice, but even then, I doubt they'd stay on the rolling dice that well.
When I started to explore dice building as a concept I was actually thinking about making a board game. I quickly realized that a digital game would work much better, at least in single player. It's just much faster and less fiddly, and you can do some cool things that are very hard to do with physical dice. There are some popular board game dice builders (Dice City, Too Many Bones, Dice Forge etc) but I haven't actually played any of them. I probably should :)
As an additional reply to this - I also (of course stealing entirely from Sanny's initial ideas) tried to make a board game prototype, and it was an absolute mess. The amount of component management needed to just make the basic dice mechanics, upgrades, + monsters, work decently was just waaay too tedious. I went with a "table" for each dice, so you didn't stick stuff to the dice but rather had a table representing each side (to make it easier to change things quickly and not mess with the weighting of the dice). I'm sure there's a way to do it though if you stream-line things a bit, but I gave up on it pretty quickly :).
Another thought I had was to use the dice Lego board games use, as they're made to be modular and accept different pieces while still being pretty even. But again, the tedium always seemed to obscure the actual gameplay :P.