============================================Is all this really less trouble than just casting a new piece? We used to do that in shop class in high school, though I don't know if the quality was good enough.
I do plan to explore that route also. I have a Foundry about 45 miles from me that Cast a lot of Aluminium parts. Years ago, I inquired about making a 503UL Head Casting. They wanted $1,500 up front to make the Mould, then Each Bare Casting Cost so much, Cheap. Not Bad when you figure (1) New Pair of 503UL Heads Cost $900 from Rotax. Just a few sets of Heads and you would recoupe your Investment. The more you have Cast at a time, the lower the unit Cost is.
Today, you have Small 4kg / 8.8lb, LP Gas / Electric, Metal Casting kit's on ebay you can buy for around starting at $450 on up, or Build your own from the many Plans out there. With these cheaper 3D Printers you can also do a Type of Lost Wax Type Casting also. My Cast 670 Head is 2lbs, my Billet 670 Head is 4lbs. So these Singles, 377/447, and 503 Type Heads are around 2-3lbs Tops.
Small 4kg / 8.8lb, LP Gas / Electric, Metal Casting kit's $450.
Med 10kg / 22.0lb, LP Gas / Electric, Metal Casting kit's $1,076.90.
With Casting you have to deal with Shrinking. I have only Cast Lead Bullets. You could probably fill in the Voids with Modeling Clay and maybe Dip the Part in some of that Liquid Rubber Coating to make it a little over size and then Sand Cast it. But I like the idea of getting it into 3D CAD and maybe just 3D Print it, then do the Lost Wax Type Casting. If you could Melt enough Material to just Cast (4) PTO Covers, or (4) Heads at a Time, would be nice.
But a Billet part would be best! With a Billet part you could upgrade it to Pro8 even.