Despite your difficulties with the form intersections, you're actually doing a pretty decent job. Your first page had some definite issues (which I outlined here), but there's definite improvement by the third. If you look at the box-sphere intersection I corrected in the link above, you'll see a similar kind of intersection on the third page which you managed correctly.

Moving onto your object constructions, you've largely done a pretty good job. Your work isn't perfect and there is certainly room for growth, but you've shown improvement over the length of the set and by the end are demonstrating considerably more confidence with subdividing your enclosing boxes and achieving specific measurements to replicate your object more accurately.

To start things off, your computer mouse is definitely a little rough. I think your proportions in the initial orthographic study might be a bit off (just based on how computer mice are usually shaped, though I have seen some that were a bit squat, they're not that common). Your construction within it is okay, though I think the front edge of the base feels a little slanted, throwing off the symmetry of the construction. That's pretty normal considering that this is the first drawing of the set, but my bigger concern is that you tend to go back over your lines quite a bit, and those additional passes appear to wobble as though you're tracing more slowly. Remember that if you're adding line weight, you need to do so using the ghosting method (which means executing the marks with greater confidence to maintain a smooth stroke). If however these are drawn out of reflex in response to a perceived mistake, that's a habit you definitely need to avoid, as every single mark you put down should be planned and intentional, the result of an explicit choice.

To that point, I'm seeing similar sketchy behaviour along your rounded corners in your toaster. Other than this, the toaster was pretty well done, but make sure you're not sacrificing your good linework practices out of anxiety or hesitation.

I'm particularly pleased with the cylindrical knob on the toaster, especially considering that those ellipses were freehanded. It's still a very good idea to get an ellipse guide for these last few lessons and challenges if you can (a full set is usually very expensive but a single master template can usually be picked up pretty cheap online, though it'll limit you to a smaller range of sizes).

As we continue down the set, you're definitely getting a lot more confident in constructing those initial enclosing boxes (which can, when done incorrectly, really impact the entirety of a construction). I'm very pleased with your lighters especially, as they convey a strong sense of solidity, but you're also getting into the complexity of the mechanisms, breaking them down into all their little components and yielding a very satisfying result that does not at any point sacrifice the illusion that each form is three dimensional.

I feel similarly for the soap dispenser at the end. The bottle does end up wider than your proportion study, simply because the initial box came out wider - but that's a non-issue. What's important is that the result came out feeling solid and believable, and the only reason we're able to identify the discrepancy is because we're able to compare the two drawings directly.

All in all, you're doing some great work here. I'll go ahead and mark this lesson as complete.