You could build cargo bike, designed by Danish XYZ company, by yourself

Cargo bikes outperform cars, but they are expensive. You can build a Danish XYZ cargo bike by yourself. The fully modular system is so simple that you don’t need complex or expensive tools. The two-wheeled vehicle can carry 90 kg of cargo, the tricycle can carry 150 kg, the four-wheeled one – 300 kg. All models can be equipped with electric hub motors and batteries.

The assembled versions are sold for about half the price of similar cargo cycles on the market. As their design is open and modular, it is even cheaper to assemble and easier to customize the XYZ Cargo Cycles by yourself. Like all modular systems, XYZ nodes enable people to create things based on the principle of using a few different parts repeatedly to create an overall structure, similar to building blocks like Lego.

The low price is largely due to the modular nature of the vehicles. The XYZ Cargo Cycles are not built in a traditional way. Unlike the singular load-bearing tube that can be used in conventional bike structures, the main structure is an orthogonal spaceframe of standard aluminum square tubes of varying lengths in which holes are drilled. Structurally, the connection system is similar to the lashed joints used for example in the traditional wooden frames seen in inuit kayaks, or with rivet constructions such as an airplane or ship hulls. The frame is assembled using stainless steel bolts, washers and nuts. The assembling requires only simple hand-held and non-specialized tools like a drill and a metal saw. No welding is required.

The XYZ cargo bikes are concepts with open source code that you can modify by yourself. The designs — including any new construction principle used in the system — and the XYZ construction and connection principle are open source codes and are provided by the rules of Creative Commons CC BY-NC-SA 3.0. Users are free to use available designs, as long as it is for non-commercial purposes. XYZ gives away the building plans and offers the assembled cargo bikes at low cost because they want to see as many of them as possible on the road.

Look at http://www.xyzcargo.com