I've tested my "arsenal" of Nerf guns, and found that the scope works best with the Maverick and the Barricade guns.
-Cheap Toy Binoculars
-Nerf Rail Clip (I used the flip up sights from the Recon)
-Hot Glue Gun and/or Duck Tape (hot glue strongly commended over duct tape)
Depending on Rail clip and Binoculars:
-Possibly a utility knife or hacksaw
Step 1: Disassemble Binoculars and Rail Clip
I was lucky and found my binocular scope already disassembled from the other part of the binoculars, so you will have to figure out how to unscrew or cut off one of the sides of the binoculars on your own. save the half that doesn't have that middle part attached (thing that regulates focus/holds them together). This obviously will become the scope part.
Flip Up Sight:
Again, doesn't have to be flip up sight, you can use another similar attachment's rail clip if you would like. however, I prefer you use the flip up if you have it since it looks good with the mod, as well as the point that the flip up on its own is completely useless and doesn't work (might as well find a use for its parts). So, either yank off or cut off the black flip up part so that only the yellow body and black rail clip parts remain. That was easy.