Dio Help. How do I...

Michael's, Hobby Lobby, any art store. The best brand I know of is Sculpey.

SteveM

mist you can pick it up at michaels or if you want to order it here is a link to there page withit also http://www.michaels.com/art/online/search?type=0&keywords=clay&pageNumber=4

Do you get the bakable clay at your LHS?  Or somewhere else?

I agree. One thing I'd like to add: Sculpey (bakeable clay) is a great way to do that and cheap for the amount you get, but I'd give it a day or so after baking to cool fully and then prime it before painting. My first few tries ended up glossy as heck, not matter how flat I could get my paint. I don't know if this has happened to anyone else. If it has, they may have an easier solution.

SteveM

That doesn't sound very doable. Many glues will eat the styrofoam, anyway. Your best bet would be the tried and true method of epoxy putty or a self drying or bakeable clay. in 1/48, there will be little texture visible and a good flat paint should be all you need.