The original "Monoprice Select Mini Glass Bed Spacer" by Sumpy adds about 2.2 mm of clearance for the bed. When I inserted this spacer and then added a 1/8 inch thick borosilicate glass surface to my bed I had to crank all the leveling screws down all the way in order for the nozzle to clear the glass surface (I even over tightened one of the screws and stripped the head a bit). I'll admit that I've replaced the nozzle with one that's a hair larger than the original nozzle. Anyway, I took Sumpy's spacer, imported it into Tinkercad and added an additional 3 mm of "box" to the right leg and some reinforcement to the base and head. Now I don't have to crank the screws down completely and have additional space between the bed and the "trundle(?)" to put cork insulation in. The work I did in Tinkercad is a bit crude but it works.

Monoprice Select Mini

No

Yes

0.1 mm

20%

Just like the original spacer you should include supports "Everywhere" (the term in Cura) when you print it.