World Models Ultimate 120s
Fitting of the heavy duty wire undercarriage is a simple task, with the tried and tested 2-piece gear fitting into a recess in the bottom of the fuse. Each end plugs into a pre-drilled hole in either end of the recess, with a large block behind each hole for the wire to go up into. You're required to drill the holes for the saddles yourself, so take the same approach here with running the screws in and out of the holes, then putting thin CA down the holes to strengthen and seal them.
When you cut the covering film over the recess, if you make one cut down the centre of the recess and then a 'T' cut at each end, you can fold the covering film down into the sides of the recess. It will then be held in place by the very snugly fitting wire gear. Before fitting the gear wires, mask off the recess area and fuel proof the exposed wood with Lustrecoat (or whatever you use for fuel proofing).