A set of hex spacers I made, very handy for electronics, quadcopters, etc...
M3 - 5mm to 50mm, (+5mm).
M4 - 5mm to 50mm, (+5mm).
M3 - Ø3mm/Ø6mm
M4 - Ø4mm/Ø8mm
There's a SketchUp file in which you can push/pull the hex spacer to your desired height.
Print it 100% fill for rough use, or >20% for static stuff.
Prints with hex face on bed.