For nose weight, get some of the Duck brand "Poster Putty" in the "business supplies" section at Wal-Mart. It's blue in color, and looks like two sheets of four strips of blue clay. It's the stuff you hang posters and such to a wall with without using nails and stuff. It comes in a 2 oz. package, so each "strip" (there being 8 "strips" in a package) is about 1/4 oz.)
It weighs about as much as modeling clay (for the same volume,) costs a little less, is easier to work with, and takes *forever* to dry out. Even when it does, it's "stuck" when dry. Heck, it's deisgned to be sticky, so when you push it up in the front of your nose cone, good luck getting it out!
On the other hand - it appears you have some epoxy on hand. You *could* simply get some lead fishing weights, drop in them in the nose cone, and pour some epoxy in to fix them there forever. You probably have a fishing tackle box with a few lead split-shot sinkers hiding in your garage somewhere. Lead sinkers make superb nose ballast.