Simple mini shelf with holes to cut down the print time a bit.

Nothing special here regarding printing, but the shelf has cutouts on the base for aligning the brackets, so print the main shelf upside down.  I've also included a screenshot from Cura showing how I printed the 2 brackets at once.  I didn't need any supports for either part.  The screw holes are 4mm, and my printer bridged them fine.

I've allowed 1mm extra space on the cutouts to make sure it fits nicely.  Brackets are just glued in place with superglue or similar.