I need to make a small spider for the top of a spiderweb cake this weekend, and I was wondering which is the easiest and/or the best to use: sugarpaste, gumpaste or marzipan. I have never used any of them - so I am clueless. Also, do you make these, or buy them already made?

Probably the best is 50/50. Half fondant + half gumpaste. The fondant gives you time to fiddle with it and the gumpaste helps it get firm.