An image of one of the produicts is at: http://www.fencing.net/forums/attachments/5936d1392842643-melting.jpg
The flat end needs a few solid layers, for the threaded insert that is melted into place. The first half-inch from that end is 50% infill around the insert, and needs a solid layer or two at the inner end for best strength. The 35mm in the "bulb" is hollow, with 1/8" walls.
If I specify 1.25mm for the Top/Bottom, then Cura puts a 1.25mm layer at the top of the infill, and this does not shrink as much as the infill or hollow sections, leaving a raised band on the outside where the Top has been filled in.
Does anyone know exactly what the Expert settings for Solid Infill Top and Solid Infill Bottom do? Could that be a solution?