In all seriousness I've been debating whether or not I feel up to grinding my own mirrors or buying them and building everything else.
This is one of several reasons I was so delighted to be gifted that extremely flat stone; it's a key tool for that sort of work.
@spmatich I had thought about a flat mirror type but fancier lenses would be more of a challenge (or more worth just buying I guess).
@Blenster you will need to set up a test staion too, to hone the parabola shape (from memory)
https://en.m.wikipedia.org/wiki/Foucault_knife-edge_test