Another method for straps is to roll out a thin bit of greenstuff onto a piece of plastic bag or something (I use a sandwich bag streched out onto a board). After it has set, you can trim it up, and position it on your model as a gun strap. It will bend easily if you made it thin enough. Glue it onto your model with superglue.
Nice red, and detail. Only thing that bothers me is that the bolter strap looks a little to long, and slack like it is not really supporting the weight of the Bolt Gun.
Other than that nice Job!