Looking for a real eye catching engine bay feature?  You'll be hard pressed to find something more unique than a glass coolant tank!  These coolant reservoirs are made with a thick high temp glass tube(good for 450 degrees), and aluminum end caps, so there is no danger of breakage. 
 
Neck design makes it simple to convert from an expansion tank to an overflow tank or vice-versa.  
Simply change the cap.  Check the store for  extra caps.  2x 3/8 NPT ports in the bottom plate allow for flexibility in connection and mounting.  1/4" Overflow nipple can be routed to drain or connected to another tank.  20psi cap.
 
Available in 1 quart (9" tall, 5.5" wide, 4.5deep) and .75 quart (6.5" tall, 5.5" wide, 4.5" deep) configurations.