That compactness is what [WalkerDev] found attractive, and in the process discovered that stacking two different Fresnel lenses and putting them in a 3D printed housing yielded a very compact ...

[Uwe] came up with a much more technical means of building a Fresnel reflector that will cook your hot dogs in seconds, but only on sunny days. [Uwe] channeled a little bit of [Apollonius] when ...