The molds are built: tomorrow I'll caulk them and seal all the porous edges. (I also have two sections that need a little more work because they're a little involved, but that's another trip to Home Depot.) After that I will put in the remesh and rebar, and then it's time to pour concrete! So exciting.
Here are some pics of things so far:
I traced the templates onto the melamine particleboard in order to make the molds.
Here's the table I refinished for the sink.
...And here are the almost-finished molds for two of the sections.