I wanted a fast and cheap to print bed level test and the other bed level tests on thingiverse did not do that at the time I uploaded this.
This design is short with narrow walls so it prints within seconds, it took the bed and nozzle longer to heat up then it took the printer to actually print this test which makes this the perfect bed leveling test for 200x200mm because with any test you want something you can print fast, see if there's a problem, make an adjustment and reprint again without waiting several minutes between each print. After this prints successfully you can choose to print more elaborate level tests but this is the perfect starter bed leveling test.
A circle is the best design for bed leveling because if your bed is not level it will start to pull away while making a circle and create straight lines. That does not happen with squares, so your bed might not be level but a square would make it seem like it is.
This is 0.5mm tall, so the printer only needs to make 2 or 3 loops around depending on your layer height. A few loops is important because the second or third loops may reveal level problems the first loop did not.
Wall thickness is 0.1 in tinkercad, I think that means 0.1mm. I printed with up to a 1.00mm nozzle and it turned out fine.
Being narrow and short obviously saves filament which saves money which is also important for any test, no one wants to spend more than necessary testing.
If you have a skirt set in your print settings it will print a skirt around the print which further tests your bed leveling. That is what the outer ring is in the photo, the skirt loop set at 10mm and 1 layer
designed in tinkercad and sliced in slic3r