Here some pictures about a Chu Ko Nu I've made last years (on the second part of the webpage - the first part is my researches about it, but written in french, so maybe not interesting here).
That was really funny to make and funny to use too. Not very accurate, but it's nice to shoot so many bolts in few seconds!
the tiller is about 75cm long
prod 55cm and 70-75 lbs (bamboo)
(other crossbows I've made here : https://www.licorneargent.be/les-arcs/arbaletes/reconstitution/ )