Had a broken off backspace arm, so using a few reference photos I made this, then fine tuned the dimensions and proportions until it was functional on the actual machine.

NOTE the arm itself is not strong enough to actuate the mechanism and move the carriage back, since it's just made of plastic, and instead tends to buckle. By grasping the arm right in front of the pivoting point, you can generate enough leverage to utilize the actual backspace. The arm and keycap just completes the look.

(You could make a much shorter, beefier arm and probably have the arm be functional, but I chose to keep the style and looks).

The pivoting bolt is not included, you'll need to conjure up an M3.5 metric bolt, or a 6-40 threaded bolt.