Ive just written an article on a bridge buiding method, you might find this useful
Ok here we go. THe girderwork is from 25mm Facia trim. Its available in 5 metre length from facia and UVPC window suppliers for only £5. I used just over 2 bits for this bridge. I went looking for an alternative to styrene products like plastitruct and Evergreen cos it’s expensive once you start using a lot of it, also this is stronger than styrene. The real boon is that this stuff is designed to be stuck together with Cyano. In this case I used the very low viscoucity “pink” flash glue. It sticks in about 30 secs and after 5 mins or so I tried to part two test pieces and the plastic broke and the joint held. So its quick and easy, in short this is all you need.
I got the Mesh from an aquatic shop, its used to seperate big an baby fish so the latter dont get yummed. The top bit is left at 25mm angle, the bottom bit is cut lengthways so its about 13 by 13mm. You can use a par of compassess pressed against the edge of the angle to score a line along it. Do this 3 times and them cut with a Stanley or similar. Use this method to make the uprights also. The 12mm flat strip you can then score in half lengthways, 3 times should do it. Take care not to go right through though.These will form the diagonal braces,cut them to the desired length and then fold them to a right angle and glue from top corner to opposite corner of the uprights Lastly cut some of the 12mm flat strip in half to make trim for the edge of the deck. http://www.smegworld.org.uk/spaf/gb/gb6405.jpg/ Spray the whole lot with a rattle can of matt black or pink or what ever you want and add the track. Knock up a couple of abutments out of the same stuff with some brass contacts and you are there.
A very quick and easy alternative to welding steel and alloy and so cheap.
The first one is about 4ft long and this next one is 6ft. THe first one is def strong and rigid enough, we shall see about the arch …
It will replace this rubbish bit of 3 by 3 which is my steam up area.
later