If it for people you know what about one of those plastic zipered notebook sleeves for pencils, pens. rulers, etc. Place coins flat and put under the floor mats. People too lazy to work are too lazy to clean your car I expect. If it for emergency maybe tape the coins in place so they do not move around.
I may do that with vac sealed ones. For family, it's because some of them expect me to spend, literally, every last dime even when I being pulled into a family activity that I don't want to do. And the idea of having more emergency coinage then could fit in the car's slots is something they find excessive. But it's pulled my fat out of the fire more times than I care to count now.
As for acquaintances, there are quite a few that think that if I have the coins and they think I should do something with them, or they need some, I should give in. I don't but it's just an extra pain in the rear to deal with. And I don't want to deal with it. For some reason having extra coinage in the care seems to make some of them think I have more cash than I do. Another annoyance.
As for thieves, well most of the containers are things that would normally be in a car. And they are getting scattered into different areas that are appropriate. The actually coin slots built into the car have only a few scattered coins in order to distract.
I will probably vacseal the coins from the next few months and then lay then down under carpets and in other hiding spots. That will be the "holy he!!" life has completely bottomed out stashes. And I like the idea that they won't clink and make noise. I've got a couple of spots where the carpet edge is loose, as well as extra carpet coverage in other areas to protect the original carpet. There's also the jack storage spot. And rather than the bottom of the glove boxes, I can pull them and attach to the outside.