Escapades With Plaster of Paris

I learned over last weekend (or, rather, I was reminded; previous experiences have already taught me this) that Plaster of Paris is rather finicky.  And that you can't let it sit at the bottom of the mixing bucket for too long, unless you desire cement-in-a-mixing-bucket.
I was *trying* to make a tombstone with Plaster of Paris, but when dumping the powder into a bucket, I hadn't planned very well and forgot the fact that it's usually best to fill the bucket with as much water you want, then slowly pour the mix in, stirring it as you go.  Because most of the time, if you don't do it like that, you'll get a large lump of hardened Plaster of Paris at the bottom of your mixing bucket/bowl/box/whatever-you-have.
So that's how I ended up trying to make the remaining mix stretch as far as possible, actually using the correct method this time.  All the while, I was stubbornly trying to smash the wet-cement-like substance at the bottom of the original bucket apart with a . . . butter knife.  Yes, I was being a bit of a dunce.  My excuse: My brain wasn't working properly that day.
Anyway.  Due to the fact that I used the majority of the mix on the previous batch that didn't turn out so well, my plaster ended up being very watery, and it took 4 hours longer than usual to solidify into a sticky substance that I needed for inscribing the words I wanted on the now-pretty-hopeless-tombstone.
When it dried, I was left with a complete maze of cracks (although . . . the words were still readable, even though that wasn't very comforting for me) and probably a very crumbly pile of plaster when I removed it.  I've refrained from doing so just yet, because I'm afraid of what I'll have to clean up.
So yes, after two Plaster of Paris projects (the first one is a whole other story) utterly failing on me, I've concluded that this area of expertise is just not for me.  I'll leave the tombstones to everyone else, thanks.