That was a bit of butchery: aluminum flat stock, a hacksaw and a dremel. I'll be glad to walk you through it, but I'm not duplicating it.

There are a few parts to the kit to do it correctly, unfortunately Horizon is no longer sharing them. Even if I casted the other arm, there's 3 pins, a spring and a spring catch necessary. I pieced it all together, but it's not pretty.

Thanks for all the tips guys!