User frankenwaeldler on thingiverse made a simple Walther P22 Gun Stand to hold his Walther P22 and 10 rounds cal. 9mm P.A.K.
The pin that holds the gun has a loose fit.
You can probably fit other guns like the Walther P99 on this holder.
The model is easy to print.
The Walther P22 gun stand was made with a layer height of 0.2mm from PLA.
Check out the design on thingiverse here: http://www.thingiverse.com/thing:1612810