So maybe you gave him all the other stuff to hold on to while you were taking them off him? I started to think you might have started to load the tray with all the bits and pieces of gear but you mentioned his hands....did he have to hold the wand against his cock but not cum? 
My original idea was to keep his hands in the stocks whilst you released the rest of him so anything he dropped would have been over the metal pan. 
It's Saturday evening here, steak and red wine finished so more ideas are fighting with my urge to doze.