Permanent tormas in the Columbarium
The term permanent torma refers to tormas left on the shrine for an extended period. Usually these are made out of precious metals, wood, clay or synthetic materials. As an example I’ve posted a few photos of the tormas in the Columbarium at Karme Ling Retreat Center. These tormas were made out of a synthetic air-dry sculpting material manufactured by Crayola. These offering tormas, called Shalzes, were made by Khenpo Karthar Rinpoche and the gyens by Ani Karuna. I’ve added a few detailed shots of the beautiful Columbarium shrine designed and decorated by Khenpo Karthar Rinpoche:
Photos by Lama Karma Lodro
tormafilm.com 
I use Fimo or Premo clay which can be hardened in a very low temperature in the oven. They have many beautiful colors including gold, silver and bronze.
I always wanted to try Fimo; hope to in the future. I’ve used Sculpey extensively. That works really well too. I personally haven’t tried the Crayola, though I think it also gives a nice result. Very lightweight though.