Rob Cruickshank built this sweet laser microscope based (at least partly, I presume) on my recent project. There are more pics in Rob’s Flickr set, including one of the custom screw-fitting he made to hold down the momentary switch on his laser pointer. Rob also reports that water squeezed from an aquarium filter is an excellent source of microfauna-rich samples. [Thanks, Rob!]
More:
More than “partly” based! Basically, I just adapted your design to what I had lying around, because I was too lazy to go to the hardware store.