Buy the way - These plastic cans are absolute lighttight. If you have some old cans (they were used min. since 30 years) you may indeed put some parts of 50cm into it (without danger).
But most danger comes from officials of homeland security : "pls open your plastic can - we would have a short look inside "
A daylight spoole would not care about - but it is from metal (not so good from point of detectors)
with regards
PS : I've some tons of plastic cans at home and use it to store everything into.
For example as piggy bank but (so sorry about) but I can't ship it to you Craig75.
And you will not have luck with some of the cans because they aren't light tight again. I've to modify it to get the coins into...