The retracting hand hold on the back of the Milan is easy to install. Installation on other velomobiles would be similiar.
Here you can see the two holes drilled in the back of the shell. I first drill a small hole with a 3/16" bit, follow this up with a countersink to carefully bevel the gel coat slightly wider than the finished hole. The reason to bevel the hole is to prevent chipping of the gel coat when drilling the final sized hole. Then I drill the hole to the final size, in this case 1/4".
What it looks like on the inisde. I glassed on the anchor point but you could also bolt the "p" clip in place. There is a 30" piece of 5 mm rope and a 22" piece of shock cord. The reason for this much lenght is so you can reach it after the rear fender is in place and replace the cord and shock cord if necessary. The top of the Milan is permanently bonded to the bottom so there is limited access. Reaching around the fender is difficult as I discovered putting the first handle on the first Milan GT.
The finished result with the rope pulled snugly against the back of the shell. The distance between the holes is 8.5cm. The previous one was a bit longer but I like the new lenght better.