Summary

This design required more cooling than fans can provide. There is too much plastic being laid down, too quickly, near the top, for it to solidify.

Instead of only applying a new layer, the hot nozzle will come by and push the soft plastic around. Some will solidify in heaps, and the nozzle may knock the whole thing over..

A sacrificial element is required. While the nozzle is occupied with it in between layers, the primary object has time to cool off. Place it about an inch away from the main object. I provided one, but use whatever you like...

Afinia settings: Must check the "Thin wall" box (or it won't even see them).
Select Support Angle "10 degrees", to minimize support.
I used 0.3 mm layers.
27 grams ABS, and 90 minutes...
Use fan cooling. Add an auxiliary print cooling fan to your printer if you haven't already done so. The overall quality of all prints is enhanced with fan cooling.

Metric-scale files are provided, in case your metric software imports tiny files.