Snapmaker advises against printing PLA with the top panel on the printer, because the environment heats up which can cause heat creep. If you still want to be able to use the top panel on the printer while printing PLA, you can use these risers. They attach magnetically (with 10x2mm neodymium magnets). 

Printing:

You should print the parts in the same orientation as they load in the slicer. They do need supports, but only very little. 

Assembly:

The magnets are pressure fit, some force may be required to insert them. Make sure that the magnets are inserted in the correct orientation (check with your printer). The risers can easily be put on the printer, and the top panel can be placed on top of the risers. You can also use them without magnets, but that way they don't sit on the printer as well.