The original model has the side supports sloping upward which on the underside print very badly and weakly as they end up as unsupported overhangs, the joints are also small and brittle breaking apart with a regular fall(happened to me, twice).

Instead of bridging the gap with straight lines i've decided to remix the model with solid sidewalls.

Remixed in Onshape.

Printed at .2mm layer height, 3 perimeters, 3 solid bottom and top layers, brim on the outside in PLA