Bruce, Someone mentioned a "jellyroll" it is padded and used to hold a photography lens. But at 4 inches in diameter and 9 inches long, it provides a nice house for the KX3 - but not much else. If you search for "jellyroll case" on Amazon you'll find two of them, one charcoal and one brown (camel).
I started out using Pelican cases but I've really found them too big and heavy - overkill - for the packing I do. The gear does go in a waterproof case, but though they are waterproof, they can't be run over by a truck like a Pelican case can.
Have a look at Lowepro backpacks. They have a huge selection of padded
backpacks for photo. I have a large one for all my camera gear it
even has a slot for a laptop. its one of the larger padded backpacks
with padded dividers. I can rearrange the padded dividers and fit key,
headset, laptop and K3 in it. a smaller backpack would be excellent
for a KX3 with room for batteries, key, wire antennas, mic and a key.
with room for lunch and a few other essentials. some even have holders
intended for tripods or in this case perhaps a Budipole.
If you are thinking of an enclosure/container/bag to transport the KX3 in a Pelican case is nice. Some of the camera bags are nice too - you can get them in either shoulder harness or backpack varieties.
That having been said, if you are transporting the KX3 in a backpack along with other things... as in a backpacking/camping trip/day hike/vacation bag my method is to put my KX3 wrapped up in my spare clothes and all goes in a dry sack. I usually take a pair of socks and lay one over top and bottom with the heel of the sock on the side, then another sock laid over 3 sides with the heel laid over the short side over top the heel of the other sock. It encloses the KX3 on 5 sides. That slides in to my dry sack and I jam the rest of my clothes around the sides and top of the bag. When I'm done I wrap the lid a few times and secure the buckle. I bet the whole contraption will float. I haven't tried it yet, though.