Do you know, that… ?

Gusset plates are often used in the design of welded structures. Not relevant, whether they were created in the sheet metal module or as a simple extrude. It may be problematic to cut profiles to this sheet.

Why problematic?

The answer is simple. You cannot trim structural members relative to non-member members.

So maybe other operations, including connect whether Impression? Unfortunately neither, because you can squeeze in one operation (subtract) many objects but only in one! The opposite is true here, we need to print one in three objects.

It turns out, that the best and simplest operation is Extrude the cut. If you have the sketch you used to draw the bracket, just point it in the tree and reuse it. If the sketch cannot be used directly, you can convert a flat face of a sheet.

Then we pull through the thickness of the sheet (here I used the options To the top in both directions) so that the cutting depth does not have to be changed when the thickness is changed. Also, remember to indicate in The scope of the operation appropriate objects to be cut.