Lid for 25mm calibration box

I use this box https://www.thingiverse.com/thing:2267549 for extrusion multiplier calibration (see here for details https://mattshub.com/2017/04/19/extruder-calibration/ ) and live z tweaking, but I also made a lid that's 26x26x7 that I print with the same settings (one perimeter, no infill, no top layers) so I end up with a bunch of these little boxes which are more useful than something I'd just throw away.

I mentioned it in a 3d printing Facebook group, and some folks stated an interest i