Want to build the lightest kayak

[Cosiona]

We live near the water, I have a yacht and various dinghies, and a fibreglass cruising kayak. But I'd like a kayak that I can carry down to the water with one hand, lift easily onto the boat etc. I'm not after performance. I want to paddle it for fitness and just to get out on the water on the spur of the moment. I don't really care what it's made of except that it'll have to be of materials I can easily obtain here in Australia. Small and light. Any suggestions?