Test tube rack E8Z

A large number of STL-files is available for racks of different shapes and sizes, for test tubes with a diamater of 15 or 16mm. Two fully parameterized OpenScad scripts can easily be used to produce one of four base models of any desired dimensions and for any test tube. The rack models have either and E shaped profile, or that of and 8 or a Z, hence the name E8Z. Z models can be most compactly stacked and a stack base is availble for that. E models can be nested together in two's or fours and for 8 models a drainer variant is available in which test tubes can be left to dry upside down.