Boolean or cuts without creating ngons I have one specific question and one general one.
The specific question:
Is there a way to boolean in a shape without creating a bunch of ngons? I want to cut a hole in the visor as seen in figure 1 and what I have is in figure 2.

Figure 1

Figure 2
More general question:
Could anyone comment on the topology of my object (keeping in mind I want to use it for 3d printing, but any advice is welcome). What could I have done better in the modeling/mesh creation. Like &quot;you used this tool here, but it created some problems in the mesh, try this tool instead&quot; I've attached a link:
Google Drive Download, ask if you'd like it emailed instead
I assume I am doing a few things wrong with my topology but I am not entirely sure what.
I am a blender novice and have watched a lot of Lydna vids and youtube vids and decided to cut my teeth by making a robot from a Studio Ghibli movie.
I thought I got the model looking pretty good, but when I attempted to 3d print it, I had some strange issues. Parts of my model were not printed. The structure underneath was, but the surface was not.
I assumed I had made some rookie mistakes, so I decided to go and try and remake portions of my mesh. This time I wanted to look at it in meshmixer to ensure everything was alright. Unfortunately, when I loaded it in, it looked even worse than what was printed out! It looks fine in Cura, but not Meshmixer... the oddness abounds.
Cut your hole >  in Edit Mode select the loop of faces inside the new hole > Ctrl+Numpad + to grow the selection once or twice > Ctrl+T for "triangulate faces" (or you can right click and it should be in the pop up menu; or go to the menu for 'faces') > Alt+J for "turn triangles into quads" (this is in the 'faces' menu too).

Not sure how well this will work for your needs, but it's quick.  GL OP