The bed is designed so that it can be disassembled into parts that are small enough to carry around or store somewhere during the day and so that it's simple enough to assemble in less than 5 minutes.
The upper section is made from 4 pieces which slot into the 3 pieces of the base so that it overlaps and stays together. There are 4 base supports set at right angles which provide stability for the bed, which, as long as it is kept dry, could last for months.
It is important to get strong cardboard to avoid damage during use. It needs to be at least 2-ply, rigid and large enough to make each piece. It is recommended to ask at bike shops for their big boxes that bikes are delivered in as this has proved to be ideal. Take care when assembling and disassembling so the card doesn't bend and need to be replaced too often.
The full instructions can be found here.