Project Orion's 10-12m variants used an external pulse unit storage that was a helical magazine. This coaster is in the shape of the magazine without a top, which provides textured surface with deep liquid drainage in the case of spills or condensation. It's a bit taller than most coasters, but not prohibitively so.
Pulse unit and magazine design is based on both
GA-5009vIII, a declassified document detailing project Orion, and
Aerospace Projects Review Volume 1, Number 5 by Scott Lowther, in particular the diagrams on page 46.
Heavily inspired by Winchell Chung's Atomic Rockets and his Orion mod for KSP, see
http://www.projectrho.com/public_html/rocket/