Hi jf - it tends to be difficult for Shell to thicken open surfaces made up of pieces that meet in a sharp manner.

Try capping your initial heart outline to be a solid (select it then run Construct/Planar), then select the top face and then run shell.

Without a solid, shelling can tend to get confused about trying to trim the extended offset pieces with each other to make a clean corner. When it is a solid there is a neighboring surface that is used to intersect with to make a good corner.


If you can post your .3dm model file, that would help me give some other advice.

- Michael