Yes on casting myself (with a little assistance) out of aluminum.
I used a lost foam process, and quickly learned a lot of things not to do. I don't have any pictures that show it off the bike.
It looks pretty much like you'd expect on the inside, with a "Y" shaped passage to the piston working area. The rectangle on top houses the two-stroke reed valve assemblies, with a third one sacrificed to make a spacer on the inlet side...
I probably should have started over after the first attempt... but I'm a stubborn one.
Litany of learning points:
Risers are important
The pouring path must be thicker than the thickest part of the piece
Styrofoam is the wrong kind of foam (two reasons: the nasty stuff it releases when burned and the terrible surface texture it leaves)
Can't fix a giant inclusion by pouring more metal on top of it
Can't fix a giant inclusion with the jelly-stuff that plugs holes in engine blocks
Cutting a long slice of aluminum with a hacksaw is tedious
Water bonded sand doesn't work outside in the high desert in the summer (hence lost foam process after 17 failed attempts at making molds)
Not enough sand on top will let the casting bulge
Cylinder stud "locator dimples" don't stay lined up in a lost foam casting
Don't wait until June to try a new skill necessary for the plan to go racing in August
I probably forgot several things in there, but all that should give you the idea.