Many velomobiles use a plastic coupling part to form a universal joint. Over time, this part wears and that introduces play into the steering. Initially, the play can be eliminated by merely tightening the bolts which hold the steering coupling in place, but as more wear develops this will no longer work.
This part replaces the original steering coupler in a Sinner Mango or Velomobiel Quest or Strada (and quite possibly other models too), removing the slop from the steering which results from using a worn steering coupler. In the first photo, the original very worn part is on the right, the newly 3D printed equivalent on the left.
Note: This is currently experimental. I have 3D printed a part like this for use on my own velomobile and am currently testing it. Because the part is in compression due to the two bolts which run through it, I think it will be strong enough even though a chunk of 3D printed plastic is not as strong as the original milled and drilled solid plastic version of the part. At 300 km, there is no apparent wear on my steering block. It is still performing well.
Another warning: It is not known yet whether it is safe to use a 3D printed part in this position. It may fail. If you print your own and yours fails, then you have done this at your own risk. I cannot be held responsible. For me this is an experiment.
Find other parts for velomobiles and recumbents in our webshop: http://www.dutchbikebits.com/recumbent-velomobile-parts
I used 75% infill because this part needs to be strong in compression and it is replacing a part originally constructed out of solid plastic. My steering block is printed in transparent PLA.
I suggest sanding the surfaces absolutely flat and smooth before use. Also rework the holes with a 6 mm drill or round file to ensure they can easily accommodate an M6 bolt.