Hi Matt, yeah like Burr says doing a boolean would probably be the easiest way. You can just cut a base shape directly with those profile curves.

A lot of times carving off pieces of a base simple block is easier rather than trying to build every surface directly to some irregular profile like it sounds like you were trying to do initially.

You just need to make sure that the curves fully divide the object when viewed from their drawing plane - if they don't fully divide the object into 2 pieces you can't cut with them.

To do the boolean select your base block, run construct > Boolean difference and select one profile (or both but maybe when they intersect one at a time might be a bit easier) as the cutting object and then the boolean will slice the solid with the extruded surface of the cutting profile and leave the cut up pieces behind. Select the pieces you don't want to keep and delete them, then repeat with the profile in the other direction.

- Michael