We needed a rack for capillary tubes, ca. 60mm in length, 5cm³ beakers kept falling over, so this rack was designed, maybe it'll serve you. Square holes 8x8mm are 28mm deep, the biggest 8x16,8mm has 25mm depth. 

Walls are 0,8mm thick for 0,4mm nozzle, so it prints quickly without awkward infills. I printed it with Devil Design's PLA, layer 0,2mm, 215degC , no supports.