*grabs a drink from my crowded freezer*
Back to work. I peel off whatever's left of the adhesive pad thing. Maybe I could've just rubbed it off. Meh.
For the absolutely clueless amongst us, what I'll be doing here is cutting a hole in order to add LEDs underneath to light the jewel (after polishing out the jewel). Mind you this whole area is not getting hollowed out, the jewel needs a rim of plastic to sit on. I decide the rim will be 4mm wide. Not owning a tool able to directly measure the plastic, I use my ruler to measure 4mm of width on some thick-ish paper and cut out a strip of that to use as my tool instead. With the paper strip and a needle I go around the circumference of the plastic, measuring and poking it with the needle to mark off 4 millimeters. With the needle's tip I connect the dots. Now the rim is clearly defined.
Now I get my leather work gloves and safety glasses on. With my utility knife I score a second, smaller circle into the plastic. It looks like this (when it's done).
Oh. The second circle doesn't need to be so close, but setting it farther away just means even more plastic to cut off later, and more time out of my day to cut it.
At the start of scoring the plastic I'm applying very light pressure with the knife and keeping it slanted backward a bit so (1) the knife doesn't jump off track and cut things it's not supposed to, and so (2) if it possibly does jump, it jumps into the middle area there that we don't care about. Pic below shows the slant.
Next pic shows how I'm really using my knife. I am not actually pulling it around with my right hand. My right hand is only holding it while my left thumb nudges against the blade to move it along. This gives me the most control over my cutting.
Round and round we go, scoring the circle deeper. My aim is not to cut completely through the case, only to dig a groove. It's needed for the next step.
This work takes a long g'damn time tbh. Better turn some music on...
That's deep enough. Now I'm going to really cut out the plastic. I stab the groove and press down while wrenching my blade back and forth in the manner indicated by the blue arrows until its tip has penetrated the underside of the xbox's cover. I pull the knife out and continue along the circumference.
Some explaining is in order. My reasons for the making the smaller circle and scoring it in before this step are (1) cutting right into the rim that I marked off would obviously ruin everything, and because (2) the plastic in that area of the xbox's cover is 3mm thick, too thick to stab and wrench at, it would take too much force to be safe for me or the xbox. The groove made it safe.
All done.
Now I reach in from underneath and trim the whole gnarly surface, cutting with a motion indicated by the arrow, gently, with little pressure. This step is not about final shaping so I stop just before reaching the 4mm rim. There's a tiny bit of slack left. ... I should say, even after all this cutting, the tip of the blade was still sharp enough to shave fur. :3 Greatest hobby knife ever, haha.
Next step is final shaping. I do this with very coarse sandpaper and I do it outdoors while wearing a respirator (not a useless covid mask) and while running a fan. Sanding this plastic turns it into superfine dust that gets absolutely everywhere into the air, instantly, and I don't wanna discover what diseases I'd get from breathing that crap. If I didn't own a respirator and fan I'd just totally wrap my face in a shirt and jump into the shower afterward with the cover and all my clothes on. You know what. Maybe next time I'll just do the work while showering.
Any grit of sandpaper from 40 to 80 will work. No fixed motions or angles are required for the sanding. Just shape the rim. Reaching in from underneath so I don't accidentally hit the exterior.
I'm going to finish the shaping later and polish the edge with higher grit sandpapers. This is the look of things now. More to come.