Introduction to PUMA Microscopy (the advanced 3D printed DIY microscope)
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PUMA is a DIY open source portable 3D printed microscope with augmented reality, fluorescence, phase contrast, epi-illumination and other advanced features. ...

An open source (GPLv3), 3D-printable microscope system, designed entirely in FreeCAD. I stumbled upon this thing this morning and thought it was pretty cool.