Interesting concept to build your own dice! Though it is a little boring to just press the Space key to roll repeatedly.
Even though I rolled enough to have all the upgrades, I could not get them to work on the dice at all. I could click to buy them in the shop, and the dice on the lower half reflected that something was changed, but I saw no real effect afterwards. In the workshop, I could not get the dice to change. The two die in the middle didn't seem to do anything, and no selection could be made to the dice itself. Clicking on some of the sides produced a different dice towards the top, but no interaction with that could be made. Sometimes clicking on other sides of the dice did nothing.
I hope you can continue working on it, even with the polish jam that is happening after this one is finished, because upgrading your dice is a good concept that I'd like to see more of.