Sweep

 From:  Michael Gibson
10389.7 In reply to 10389.6 
Hi Tony, so yeah you can put in an arc using arc 3pts like this:



Then prepare the rails by joining together the edges so you've got 2 long closed
curves as described above, then you can select the arc and run Construct > Sweep,
select the rails and get this result (3dm attached too):


- Michael