I don't of much GIY activity. Lens elements are cheap enough on the surplus market that grinding doesn't make much sense.

Reinhold makes and sells meniscus landscape lenses using stock elements. Astro lenses are, needless to say, very narrow field - though people do play around using the objective lenses from old binoculars.

The book Primitive Photography has quite a bit of discussion on the topic of making lenses from stock elements. http://www.amazon.com/Primitive-Phot.../dp/0240804619

I've often thought of going through the Petzval patent and designing a lens using standard elements from Anchor Optics or the Surplus Shack.

The Oslo lens design program has a free educational version for lenses with 10 or fewer surfaces - enough for 90% of non-zoom photographic lens types - http://lambdares.com/education/oslo_edu/

Kingslake's book goes through the classical lens design methods - Petzval sums, thin lens formula and such - http://www.amazon.com/Design-Fundame...ke+lens+design