I suspected. That's really nice work you've done there. Nice to see what you used for the wall drain as well. I was thinking either a spindle or possibly a piece from those Diskman type earphones.
I love insulation foam, sadly since I moved to AUstralia I have realized it's a rarity here. Been to two large "lowe's" type stores and no one sells it, they still use the fiberglass stuff exclusively.
Pic related. Sadly I don't have any of the good pics on the new laptop but you can get an idea there of the TMNT sewer I was working on.>>7755202>>7755211
I recommend Apoxie Sculpt, Green Stuff or Tamiya modeling compound. Apoxie Sculpt will be the least expensive and you get tons of it. I also recommend geting a NECA base or something with a foot ped if your figures have foot pegs, otherwise a Tamashii Nations type gripper stand and sculpting over the stand.
You wouldn't want play dough because it doesn't harden and over time your figures would fall over even if you don't touch them. Essentially what >>7756054