alterd arm for firefly 150

added wire hole on top part of arm

made holes slightly bigger on the lower half of arm to suit my screws

lower arm comes out missing bits in slic3r for some reason but prints perfect with simplify 3d ?

also don't no why its such a big file but I'm only using 3d builder ( windows ) till I can get my head around fusion 3d :)

but printed fine and works