I've used this simple tool for years and haven't damaged a single cover upon removal:
http://www.beyondbikes.com/
It is manufactured by a company named Enduro® for pulling cartridge bearings. In the QBP catalog it is #TL8900. It is designed to fit inner diameter openings of 10-20 mm (like a hub cover). They're available from Beyondbikes.com and also various other internet sources for only around $4.50 - $6.00. And it will probably last forever. [Whadda deal!]
A small simple tool (around 55mm long). The hardened black "feet" slip into the inside of the cover, then you can wedge a diiscarded (long) axle or Large Philipps screw driver through to the inside of the bend of the tool, and just tap briskly from the opposite side of the hub. Covers pop right off without deforming any of the inner edge.
I just use a rubber mallet, working it slowly around the edges of the cover, to tap the covers back on.
Bob Hanson, Albuquerque, New Mexico, USA