An excellent addition. Printed on an A1 Mini with SUNLU PETG, added mouse ears at the corners, 30% fan max, no sign of warping. The gap for the Z-axis turned out to be such a tight fit that I didn't even have to tape the box down, it's a solid clamp. One minor nitpick is that the box sticks out 1 millimeter on the right side of the printer. But my printer does do that thing where it dips the nozzle down between the buildplate and the box after the first layer, so I'm happy with the space it leaves for that.

Excellent. I had seen one with a handle, but I prefer this compact version. The only minor criticism I have is that the filament threading clip could benefit from a little more surrounding support to keep it plugged in better if I fiddle with it.