I have managed to get around the grabbing audience situation (very common in church 'all-age' services where cubs and brownies try to get at the stuff) by using a 'dump bag. There are two ways I do this, the first being a Wlkinson's linen basket which folds open and has velcro to attached the bag to it. This has a couple of extra bags in (get the black one if possibl it masks contents whereas other don't) and as the trick is done I get the appluase (sometimes

) and then ditch the trick. This means at the end everything is in one place and can be taken away by me at the end or removed by an assistant to a safe place. The cost of this is less than a fiver!
I also do the same with a wicker linen basket, which has the benefit of being totally solid and has a lid which protects from hands and eyes! Again, less than a fiver for a very adequate tool.
I am currently working on a desing which enables tricks to be brought out, used, stored/swapped, etc. which has a mechanism that enables it to be shut and left shut (unless you know the secret of a certain Mikame box

) - should be practical and secure and being made of MDF around £25 all-in. I will publish details of this when I have perfected it for others to see (photo's will abound) and copy (plans will be made available).
Hope this helps,
Vic