The Palette+ is an excellently engineered product, but it has one minor annoyance - the SD card can accidentally be inserted between the case and LCD board, or dropped into the case. This add-on "funnel" directs the SD card safely into its slot.
The face that touches the outer case should be facing upwards when sliced - see Thingiverse preview for the orientation. Shouldn't need any supports, though there will be some bridging.
To install, remove the top cover and slide onto the circuit board.
I've only tested this on one Palette+, so it may fit differently and may need adjustments on other units.