I made these for the myriad of car combat games I am play testing. They are drop weapon markers representing oil, mines and spikes. We used teddy bear stuffing for smoke. The oil was the most impressive creation, it uses 2 part resin (Pour-on) colored with ink and pastels. The mines are buttons with plastic card on top, and the spikes are chunks of sprue. I like those the least, but a simple solution for a "true" spike eluded me and this was a simpler alternative.
Enjoy your Sunday,