Ages back I got a set of 6mm water cut aluminium quick jack plates from Chris Lidgerwood. I welded them up with the MIG and they turned out pretty good.
I've polished a couple of them up and made the mounting rods from 20mm aluminium rod and tapped it at each end for 12mm Stainless button head cap screws. I'll try to remember to take a pic of one bolted up.
I don't have any templates as such but there are several different designs out there so you could make up your own design easy enough and it'd be hard to pick.
Here's one just welded
Cheers