Working with Andrea, a grad student in the Calve lab at BME, over several interactive design sessions we built this. The original requirement was "Place a force equivalent of 1-4 grams onto embryonic collagen and image it in a fluorescence microscope to provide a three dimensional image of its response to the force over time (It should organize and we'd like to see how that order originates) Things naturally started complex, stepper motors, flexures, force sensors for feedback etc. 

We ended up with a ebay bought, $30 record player tone arm. It has a built in 1-4 gram adjustable weight in the back originally to set the needle tracking force. A teflon pad in the front is at a slight angle to apply the force normal to the optical plane of the scope. Seems like cheating.