Hi and welcome, just get stuck in! Building the chassis in the best bit i think because it starts to look like something in no time, i used one of these to clean up the ends of my box section once i had cut with an angle grinder, just keeps the ends nice and the correct angle
http://www.ebay.co.uk/itm/Sealey-100...AOSw0e9Uy5p 2
not the exact one i used but this kind of thing
Rosco