I went looking for the single layer test print, I couldn't find it within 0.06 seconds so I just made one up real quick. It should obviously work with both the MK4 and MK3's as they are the same build volume :)
Printed at 0.2mm layer height
I used eSun's Cool White filament for the test print
If you accidentally (or impatiently ;) ) bend the test sheet, you can heat up the print bed to around 70 degrees and place the sheet on the bed. In no time you'll be able to make the test sheet flat again. It happens, I get it. Just don't burn yourself
X1C and P1P Single Layer Test can be found here: https://www.printables.com/model/473123-bambu-lab-p1p-one-layer-test-02mm
The author marked this model as their own original creation.