Suspention

do you want the subject visible through 360 degrees in the case, or will you be limiting the viewing angle?

The means may be to limit the field of view by means of a shadow box.  Supports are then strategically placed such that they are hidden behind an object which blocks their view from the front.

0621,  i suspend a c-47 skytrain from a glass case using magic line from Revell Magic Flight kit. i glued the line to the wing tips, then to the inside of the case, i used molding around the outside to hide the glue spots on the inside of the case. i had to go to ebay to find the Revell kit, or you could try your local magician shop for magic thread. it will have little or no visability.