Yeah, I have a 3ml syringe plunger as the stopper for my current fill hole, so that's one option. I really like the idea of the thumb screw though. Seems like it will be even more convenient. The 20ml syringe tube I'm using seems too thin to hold a screw, so I haven't tried that.
Perhaps a self-tapping wood screw? Grind the pointy end off, and maybe the threads will be far enough apart to fit around, and grip, the wall of the syringe?
I love your sig BTW. I just about choked on my vapor reading that.
Thanks for the help. I'm definitely going to get 1 or 2 and play around. I may have to visit the screw dept of Home Depot.
Did you follow the link? Would you like to buy a monkey? made me laugh hard enough my wife asked if I was alright. The quote in my sig is just the most memorable line from it