I started with a Malmos engineering bike carrier with a swan neck flange adapter. The bike carrier has a tubular upright which slots into a socket in the base plate. So it was fairly easy to find tubing to fit into the socket. I then used a Tubeclamp three way 90 degree elbow to joint the short vertical tube to the horizontal arm sections. To get the horizontal arms to run parallel I had to get a local engineering company to bend the tubing to provide me with a short section set at 135 degrees on each section of tube. The rails for the trike are offcuts of steel palisade fencing and they are fixed using exhaust clamps of the appropriate size. It isn't exactly lightweight but it was something I could put together relatively cheaply and with little outside assistance. As the design has utilised the bike carrier base plate without modification it does mean that the two carriers are interchangeable.