You can make one but why bother? Go buy another finderscope that's got the right angle already built in. That way you can have the best of both worlds. The first thing that you have to do is to accuratly measure the FL of the scope, cut the tube and make a right angle holder for the diagonal mirror (1" newt. diag. is fine) and put it together with the EP at the same distance taht it was. That's a lot of machining and threading so that adjustments can be made for focusing. Really a lot of work for something so cheap.