I've tried the on-site sculpting station with a legacy family I used to have, and it didn't work for me. I usually convert a vacant residential lot into a graveyard lot to serve as a family cemetery (obviously I didn't do that with my Immortal family, as edit town is off-limits), and my desire was to place ice sculptures of certain sims there as memorials. The sculpting station wasn't available in the buy menu. That might have been a graveyard specific situation, though.
I know for a fact that I can place portraits and photographs on these lots, as I've done it. But as this kills the appreciation value of the objects d'art, I won't bother here.
Edit: The above post gives me an idea (unrelated to this thread btw). I wonder if the sculpting station will still be there if I place it on the lot first, then convert it. It's worth checking out I suppose.