Discussion

The design we introduce here provides a foundation for microplate storage in an open-source robotic system and demonstrates that this can be achieved at minimal cost.
Although ambient plate storage is suitable for some applications, in other cases incubation may be be needed at a particularly temperature, or at a particular humidity or gas composition. It is possible to imagine extending this design by encasing the frame in an insulated/airtight case to achieve these aims. Instructions for building a CO2 incubator are already available from the Pelling laboratory and might synergise well with this design.
Similarly, a barcode scanner could be added to verify plate identity and minimise the possibility for human error. The advantage of an open-source design is that such improvements can now readily be implemented in future iterations. 

Supplemental files and instructions

Parametric 3D design

PlateStorer.scad - this is an OpenSCAD file. It is a script which generates a complete 3D model of the device, including all 3D printed components. It can be used to explore the device in three dimensions, and to edit the design to incorporate new features.

Stereolithography files

Download all STL files
ZcarriageA.stl and ZcarriageB.stl. You must print both of these files once. Mount a piece of OpenBuilds extrusion to part A with M5 bolts and drop-in tee nuts and then mount part B below this extrusion to set the range of movement for the carriage. Use M6 bolts through the 6mm holes to mount 606ZZ bearings (flanked by large washers) to act as pulleys for the GT2 belt. Attach a GT2 pulley on the shaft of a NEMA-17 motor and mount the motor to the Z-carriage using M3 bolts. Place the T8 nut in the holder and mount with more M3 bolts. Mount the whole Z carriage assembly to a mini-V gantry with M5 bolts.
BeltattachmentA.stl and BeltattachmentB.stl. Print both of these and clamp them together with an M3 bolt and nut to join the two ends of the GT2 belt together. Next drill a hole in the stainless steel sheet and attach to BeltattachmentA with another M3 bolt and nut. The stainless sheet should also be drilled with two further holes in order to attach to a mini-V gantry plate.
MotorHolder.stl and BearingHolder.stl. Print one of each. Mount the motor with M3 bolts. and mount both to the extrusion with M5 bolts and drop-in tee nuts. Set the 608ZZ bearing in the bearing holder.
ShaftCoupler.stl. This can be used to clamp the motor shaft to the T8 drive screw. Alternatively a commercial coupler can also be used.
PlateHolder.stl. You will need 4 copies of this print for every 6 plates you want to store. Mount to linear rail with M5 bolts and drop-in tee-nuts.