I dont know if this has already been suggested. The ability to take a sketch line and split an object. Basically how an extrusion works now (when a closed sketch is extruded into an object, the extruded body deletes any other body intersected.)
The idea is that either single or multiple lines could be selected and the promt to “Cut” would appear. When selected the typical gyro will appear and enable you to move the line, only now creating a zero width line through the obeject. Two other options should appear while cut is selected, “Loft”, “Trace”. Loft will do the same as the looped loft would to another, travel a straight path and adjust size as needed. Trace, would run along a perpendicular line till the object has been completely cut through.
When used the line should only cut fully through an object. This would be necessary to avoid creating a face that cant be mended and cause the app to crash.
This feature will allow those using the app to easily slice parts that may have been unioned, or allow you to builed the part fully together and cut individual parts off of it that may need to be cut off and exported by itself if it needs to be fabricated as a individual piece. Unless im mistaking, the only want to do this now is A: redesign the item for separate export, or B: design it to the side and add it to its repetitive object.
Next, then adjust the angle to 90°, and click 
Done. I think that will give you the plane you are looking for, then split the body as 