I wanted an air compressor since I had a lot of pneumatic tools, but again space, so I put it in the attic.   The only visible sign is the air lines, guage, water trap and drain valve.   All compressed air systems must have a way to trap and drain the water which condenses from the air when it is compressed.   I turned the tank on it's end with the high pressure outlet on the bottom (so the water would drain), ran this 1/2" line down about 2/3rds of the way to the floor in the shop below, then teed it into a 1" line.   The 1" line is the water trap and goes almost all the way to the floor then almost to the ceiling on the top.   The air must come down from the tank in the 1/2" line then slow down when it enters the 1" line (cross sectional area is about 4 times that of the 1/2" line so air velocity is about 1/4) and climbs back up to the ceiling.   This "slow down" allows the water to condense and collect in the bottom of the 1" line.   The bottom of the 1" line stores the water, and there is a 1/2" outlet at the bottom of the water trap which goes to a valve and then outside so the water can be periodically drained.   PICS   Please see my Air Compressor Page

I had a bunch of 18V DeWalt cordless tools which use the same rechargable batteries so I needed a recharging station.   I have converted most tools to the 20V Max batteries.   I attached a 1x6 shelf to the wall near an extra outlet in an out-of-the-way spot.   The shelf stood out from the wall 3/4" so the cords could be passed through.   I attached a spare plug strip to the bottom of the shelf and, voilla, a charging station.   PICS   Also please take a look at my Tool Storage and Charging Rack Page.

The Air lines from the compressor in the attic.   You can see the larger pipe behind the others is the water trap.   The upper valve, just below the guage, is the main in the line from the water trap.   The lower valve is for the reel in the top right corner.   The water drain valve is out of sight near the floor.

A look at the lower end air lines.   You can also get a better look at the hose reel.

Charging station hanging from the ceiling above the 10" bandsaw and drillpress.