It's a bit of a rough guide, but has been done this way before! However, if you're going to give it a go this way (as opposed to more expensive silicone moulds and vacuum casting), make sure you find the right materials:

> UV stabilised (stops clear lenses from going dull and yellow)
> Good strength (otherwise it will crack and fall apart)
> Good heat deflection (otherwise will distort)
> Low shrinkage rate (otherwise your parts will shrink after moulding and may not fit)

Note their comment under performance of their clear UV material:

"Castings can be displayed outdoors after priming and painting. Unpainted castings will yellow after being exposed to UV light or excessive heat above 115°F/46°C".

This won't cut it. You need at least 80°C heat deflection (100°C better) in the Australian sun, otherwise the lenses will simply crack or warp. I use an automotive grade (building a bit of a library of alternative materials) for my lenses, even that turned dull and yellowish after approx. 2 years exposure in the UV tester at work. This is acceptable for tinted red or amber lenses, no good for white opaque or clear lenses. Cheap grades of resin will literally turn solid bright yellow or opaque brown overnight.

Another option is painting your lenses with clear UV paint afterwards.

Got some other tips if anyone's keen...I'll post up some pictures of my lenses when I finally finish them (nothing seems to happen fast in China)!