Hex styrene rod

I am looking to fab some nut and bolt heads and can’t find a source for Hexogonal rod. My hobby shops don’t have it. Great Models site doesn’t list it. Does this exist? I’ve seen others fab bolt heads but maybe the material they are using isn’t styrene. Ideas? I’ve tried modifying round rod but this just never works out right.

Got some in three sizes at Niagara Craft & Hobby last year. See
http://www.plastruct.com/Pages/Action.lasso?-database=PI.PRODUCTS.fp5&-Layout=Complete&-Response=OnlineProductDetail.html&-op=eq&CCode=MRX-40&-Search

A good source for every bit of styrene you can imagine is Plastruct, I got hex-rods from them myself. No problems with ordering and delivery. The only draw back is that the site is somewhat hard to navigate.

Niclas
http://www.plastruct.com