daisy this is what i did, just lay three sections of track side by side with about 0.5mm separating them now you have your length & follow Tanques technic for the u brackets, I drilled a hole in the bottom of the u bracket & solder some brass rod in to make a spigot, I used plastic strip (4mm w x 1,5mm thick) for the base then drilled holes to attach the u brackets.