This is a mount for 2 Optical IR sensors to be used together to determine water level. There is a void for 2 rectangle ceramic magnets to be inserted while printing. Using Cura or something similar, use post-processing extension to insert a pause in the print at the layer just before enclosing the void. In the void, place a little super glue and insert the magnet, wait a few minuets (otherwise the magnet will be attracted to the print nozzle) for the glue to dry and finish the print