Honestly ? I'd just buy the really thick mini zip bags and use those. They lie flat, they're pretty waterproof and they're very transparent.
The ones I mean are the ones sold for jewellery wallets. They are much thicker than the usual ones.
Pm me an address and I'll put some into an envelope and post if you want.
A few small ones will easily fit in a slightly larger one and it'll lie as flat as a wallet.
Like these.
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