Limit Support to Certain Areas?

[VmusicV]

Hi, I am making a "holder" for a small USB hub. It is the shape of a rectangular frame - where the USB hub will "slide into it" in slots in the side of the frame - see pics. I want to limit where the support is. For example - somehow tell the slicer to only put support in this or that area, and not in other areas? (the holder will sit under or on the underside of a guitar pedalboard; which is why a holder is needed) I am using Bamboo slicer (mostly because my printer is a Bamboo and I can wirelessly send the file over to print)...... I am open to another slicer. When I check the "support" checkbox.... the entire area, the empty center area AND the slots in the side of the frame shape get supports. It's way too hard to clean out the supports in the slot area on the sides. See the pics. Any thoughts on restricting the support? TIA, AJ