Five is the magic number (or at least it is for Royal Mail...)

My sister sent me a Lego man.

To be precise, it was a little collectible mini-figure in an orange packet and I loved it!

Unfortunately, while it fitted inside the small envelope with her letter, it was more than 5mm thick; so it didn't count as a standard letter, it counted as a 'large letter', which takes a special stamp and costs 11p more. My sister hadn't realised this and had posted it with a normal stamp, so they kept it at the post office - where I picked it up and paid a £1 admin charge (as well as the extra 11p).

I don't really mind, as that's just the way the system works and they have to draw the line somewhere (and my sister wasn't to know so I don't blame her in the slightest... plus it was fun receiving a special package!) - but it got me thinking... Just how much can I send with a standard stamp?

What kind of things can I find that are 5mm (or less) thick?

I think I feel a challenge coming on!