Kneadatite[1] (aka "Green Stuff") which comes as a 'tape' of yellow and blue putty side by side (and becomes uniformly green when you get the base and accelerator mixed completely) is a handy form, much used to make small models. There are also wood-colored putties for filling holes in wood, and even marine-grade ones that can be used under water. Epoxy is amazing stuff!
Also a readily available and inexpensive alternative that is even better for some applications is gas tank repair putty like Waterweld[1]. It's great for repairing door knobs, or your glasses in a pinch. Also it's available at almost any gas station for $5.00 for a tube. It works very similar to green stuff and has gotten me out of a jam more than once. It's sandable and paintable, also sets under water (or gas). Just slice off a chunk, knead, and apply. Sets in a couple hours, fully cured in a day. Also it's shelf stable for basically forever.
I do love sugru for all sorts of stuff though. Especially building custom connectors for electronics wiring harnesses and hanging things on tile without messing up the tile.
1: http://www.polymericsystems.com/epoxies-adhesives/epoxy-putt...