I'm working with gumpaste for the first time.  I made baby alphabet blocks out of solid gumpaste from a home recipe.  They are starting to harden and I noticed how uneven they are.  When they are dry, is there some way I could shave them or carve them to form perfect blocks?

You can always try! I've never shaved gum paste but you can try using a sharp knife to scrape away and see what happens.  It could work! 

gum paste when dry is fragile, occasionally, you might be able to shave it, but you would probably end up with a lot of breakage.  One thing you might try is to very gently file down the rough uneven areas with an emery board.  I don't know it it would work or not but you can try it. Make extra for sure.

shave gum paste yes --

carve perfect blocks out of hardened gum paste--tall order -- be real cool if that worked for you --

for going forward-- make 5 gum paste squares ( i would use fondant + cornstarch kneaded in)

and place them around a block of cake or rice krispie treats--you can cover the joins with tiny piping --

or you could miter the edges after drying and fit them together --miter with a microplane

could do it with chocolate or marzipan  too --

gum paste would be the last medium on my list

i've shaved it with a potato peeler to get to the good stuff inside when i stored it and the outside hardened

I have filed it with a clean metal file with no problem, although just small amounts - rough edges and slight contour changes.