Angle Cut Proper Technique

I am working with my son (6) to design an x-wing model we can print. I found one on thingiverse, but wanted to go through the process of creating my own. I am currently trying to mimic some of the features of the model I found, but I’m not sure how to cut away material at an angle after extruding. Here’s what my sketch looks like:

Here is what the one I’m mimicking looks like. Notice the angle:

So how can I cut my model along this line?

Or should something be different in the sketch to make this simpler? I’ve tried using the subtract tool with an angled piece which I can get to work on a single wing, but how to get it uniform on all wings is eluding me. Any ideas?


Awesome! Thank you so much. That’s perfect!

And since you mentioned it, how are you recording videos? Is this a feature of the app?

Thanks again for the help. So, now I’ve got most of the corners cut, however, cutting has stopped working or I’m not doing something correctly on this last one.The corner on this last one won’t cut and the pillar on another one won’t either. Here’s video to show what I mean.

Yep. Tried the wall from the opposite side and tried to remove the entire pillar. Nada.