Summary

I noticed some spare holes in the front corner parts of the original MicroCube printer design and instantly thought about a CoreXY conversion. I had trouble with the stiffness of the x carriage with the original H-Bot construction and this seemed to solve it.

Just print the new x carriage "x_carriage_coreXY_improved.stl" and the "x-carriage_tensioner_flipped.STL" for the other side. Also add 2 more U grooved bearings. Make sure one pair of bearings is above the other, so the lines don't rub on each other. The other files are only needed if you want to modify the SCAD.

Combine this with https://www.thingiverse.com/thing:2983755 for an even more precise system if you have trouble with slipping / moving fishing line. Also the top mounted part cooling fan with the long tunnel to the bottom never worked out for me, so I designed a combined shroud for hotend and part cooling https://www.thingiverse.com/thing:3569037

Overview of the printer: https://youtu.be/99TClrjy2WY

First print after the conversion: https://youtu.be/YBdoyKuMLBE