Play around with the settings when you print your clips. Maybe under extrude a bit so they will fit easier. Also, I am printing with no top and bottom layers, just 2 or 3 external walls and no infill. This way clip will come out flexible, similar to what Paso has suggested in his link to Thingiverse. Also check your print settings, the temperature of extrusion especially and filament quality. I am printing at 230C but that’s because I need more speed, test it on 210 or 220C. So far I have printed about 15kg of TRP tiles and those pillars you are talking about broke of in maybe 4 tiles, which were printed with 3-4 years old cheap filament. So definitely there is a room for improvement.