Did you put studded tires on it as the year end cooler weather is starting
Make it a snow cat!
But seriously about the real great achievement of the machining, I was wondering how you transferred the measurements for complex milling from the frame to make engine mount parts.
If a high-tech camera takes a picture of parts and a gerber file is made for CAD I suppose that is a way to do this. I really know very little other than the names of some things about CAD, but find it amazing.
On the lower tech side I know going to Tap Plastics and getting stuff to make a mold could be a way to do this, then you can get the changing radius of a curve in one dimension and then 90 degrees opposed do that again and sort of get multiple points measured.
Just taking a calipers alone and measuring directly from the frame tubes you say are oval shape would I think really be challenging. The way I have gotten some things to fit is the last mentioned and then making a slight bit smaller and grinding final shape to fit. That can be hard to do and often is not anywhere near perfect.
Although I can say that the way whatever is it that Japanese wood temple buildings were made by old time crafter without glue or fasteners, that is sort of analogous to what I sometime attempt. Measure, look, and carve but in metal.
Heating up stock metal in a crucible and pouring molten metal into a waste mold would be fun I suppose too. I had taken a sculpture class and gone on a field trip to a foundry and seen this method. I had also seen jewelry made with this method and none of the near microscopic shapes were lost in molding.
I did the eye ball and some measuring and welded a platform to my steel 60's era JC Penny Foremost frame so I did not encounter too many problems. A hub I made with washing machine pulley and getting to clamp to spokes and the cone shape the spokes make have been the most time consuming part of my current build.
Measure Twice