This kitset is the cheapest way of making a bike trailer of any size. It provides a towbar, two towbar bolts, a saddle for extra strengthening of the towbar, four wheel dropouts, and the quick release hitch. You provide the wheels, screws, glue and the wooden frame and a couple of hours of construction time later you have a very useful and relatively light & strong trailer (once the glues dries). 90x32mm Decking timber or 75x25 fence palings are a suitable wood. Cost is $95 + $25 courier
There have been four workshops in Christchurch where people have made their own trailers in bulk. Read how they have gone & see photos with links below. See the Biketober website for details of the 2022 workshop when it is getting near October. Oxford Terrace Baptist Church generously hosts these events as a way of encouraging people to care for the planet / God's creation
Instructions for consructing a wooden trailer
The 2018 wooden trailer workshop
The 2019 wooden trailer workshop