I recently bought myself a new toy! Tools can be toys so I don't want to hear it. I picked up some Super Sculpey so I can start making maquettes for me to use as a source of reference for future illustrations. Sometimes it's difficult to figure out how light would fall against an object you made up out of your head, so it can help out a lot to sculpt some simple shapes just to figure out how the light reacts and where the shadows fall. Ideally, in the end you get a more realistic and believable final image from it.
Here are a couple of first attempts with the Super Sculpey. Not trying to get too extravagant, just trying to get a feel for the stuff since I've never touched it before.
And here's my study based on the bottom-left photo. It definitely helps me move along more quickly because I don't have to try and figure out how it would work, I just follow the information I can gather from the photo.