A wall-mountable arduino (UNO & mega) organizer & cable holder.
Holds 4 UNOs & 2 Megas.
I had too many arduinos lying around - so threw this gem together in SketchUp in a rather short period of time - evidence for this is seen in the pictures where the mega is located. The original file didn't compensate for the USB-B port overhang... so I improvised by utilizing my soldering iron. Its not pretty, but I didn't want to reprint the thing (I already drilled holes and mounted this thing).
Don't fret - the I modified the file so there's plenty of room for your Arduino Mega.
You can use a raft or not... up to you!