I build one from 1.5mm airplane plywood. It weights ca. 12kg/27 lbs. I test it on hiking trip in Lapland and it was great fun.

Backsplash V2  –  a backpack kayak  (3555 x 670mm   11` 8” x 26 3/8” )

With backsplash it is possible to combine hiking and paddling during same trips. It has separate carrying system which is comfortable and strong.  Backpack frame can be stored over back deck while paddling and hiking gears can be stored inside hull while hiking.  This is version 2 of s&g backpack kayak. Version 2 is 425mm longer compared to original boat. The middle part is exactly same! Only bow and stern parts are longer, so if you have built the original version, you can update it by just building longer bow and stern parts. Version 2 is a bit faster and it can hold a bit more gear or bigger paddler. It is still a very small kayak! Big paddlers might feel that cockpit is a bit small. I think that max paddlers weight is ca. 93 kg ( 205 lbs )

Below is links for rotatable 3d models. They work best on computer, but can also be viewed by phone. ( models show older shorter boat ) It takes a while to load model. Exit model by clicking back on browser. 

It would also be handy on fishing trips to remote lakes or as project when building or storage space is limited.  Living on city? – take a boat on your back and walk to shore to for paddling?

plans : http://www.duckworksbbs.com/product-p/pk-backsplash.htm   

Video below shows bike-  and hiking trailer setup. No plans yet, but it works so great, that I will draw them later.

Read here John´s story of building and paddling of bigsplash ( older version of this bigger backsplash )