Following on from the thread about a properly ugly bike seen on the WOL we discovered there is a fleet of them based on a open source design. Only the recumbent is fully planned out the cargo bikes are a commercial venture to fund the programme. They can be bought for a reasonable price, a workshop is ran in Copenhagen or they're happy for one to reverse engineer from photos.
The trike has a full bill of materials and detailed plans though so maybe a good place to start before some reverse engineering.
I have priced up the aluminium tubes and fixings, the frame comes to about £150 before labour. Which in this case would be free. Probably the same again for bike parts.
Not sure on the front wheels, think they could be expensive.
FRONT WHEELS 24”x1.75 equipped with a reinforced axle (M12, 8.8) for one-sided attachment, prefarably: mirrored drum brakes or disc brakes and a double break lever for synchronous braking of both front wheels
The rear they spec a nexus hub but I've seen derailers mounted so I think unless a cheap internal geared hub falls in my lap that will be the approach.
Blurb about the project is here
http://www.n55.dk/MANUALS/SPACEFRAMEVEHICLES/spaceframevehicles.html
And the plans are here http://www.n55.dk/MANUALS/SPACEFRAMEVEHICLES/DIY.pdf