Here's a great, cheap, 100% waterproof case for G1X.......

Hi Roberto,

Mine came with a corrugated soft synthetic rubber liner.  You can see this in the photos in my OP.  It can be removed to leave the hard plastic shell only on the inside.  I believe you may be able to order a pluck foam block at extra cost - perhaps check with a supplier, but that wouldn't work for the G1X because that model almost completely fills the box - there's no extra room and the rubber liner is perfect.

I've heard back from a few other people who've tried this box for the G1X that they found it a tight fit in the dimension from the back of the camera to the front of the lens cap.  After some discussion we narrowed this down to the specific filter adapter, filter and cap they were using.  Some adapters and some filters and some caps are fatter than others.  I'm using the Canon adapter, a thin Hoya protective filter and a 58mm Canon DSLR lens cap. This combination works fine and the G1X without any of the accessories fits very easily.

Another solution for making custom foam shock absorbing liners is to use closed cell foam.  Buy yourself a cheap thin camping sleeping mat made of the stuff and cut it up to fit whatever you're putting in the box.  It can be easily glued together with silicone rubber sealant of the kind used for guttering and roofing.

For anyone interested, the top-loading Model 609 Dry Box works very well for larger cameras like DSLRs.

Cheers, Rod