If you do decide to make one.
Here's a couple of things to remember.
On a brake, heavier is better.
Which means... the thicker the metal used to make it, the better, and longer it will perform.
1/4" is the minimum.
With basic cutting and drilling tools they're easy to make.
But if you want crisp, clean break lines.. then the face should be milled to a 45 degree or so angle
If you take a good look at the bent metal in the picture you posted..
You'll see what I mean, that brake doesn't have a machined face.
And the brake line isn't exact
Just my 2 bits worth.
I actually bought mine some years ago from Harbor freight.
Then spent a lot of time re-working it to function properly
"Bye" Bye" Riceboy
(Ex-wife fore sale... take over payments)