Most spinners are elliptical.
I have found that the extra flywheel weight helps most engines idle smother, more reliably and at a lower rpm.
just sent you a meassgeI'm on this site for very similar reasons as the op, i have 40 years building model airplanes. Some parts of what we do (pun intended) cross over into lathe/ mill needs so here we are.
Spinners look great btw.
hey thanx yes Im interestedIf cost is an issue you can always make a norman style QCTP for a fraction of the cost. That's what I did. Lots of forum members have made them. Not hard to make. Can be made with just a lathe and a drill.