It's easy to make a brake, you just need the right stuff.
If you don't have the right stuff it would be easier to get a new one from a cheap scooter,...
I cannt tell you right know to make it best, cause I've to test my break for a time before I can tell you if it's any good.
I took a aluminium, 13cm x 3cm x 0.8cm
At my first model I just drilled a hole which made it impossible to use the feather ..
So my new model is going to be with two extra plates which are the link to the (screw)Axle of the break and gives the feather space to stay in.
But you also have to bend the alu-> get it in the oven and make it as hot as possible then hammer it to bend it, there are many different ways to do this, ...
If my break is working, I'll post it in the forum, but that will take me 3 weeks cause I'll writing an examen in 3 weeks and have to learn.