Adding pickups covers.

[JMP/HBE]

Did you check for electrical continuity then?

My issue isn't keeping the covers in place, as they're P90s, secured by screws that go through the covers and the pickups. Rather, I'm concerned about the covers acting as little antennae, gathering and focusing hum into the coils.

I don't have that problem the pups are already grounded before the covers. P-90's are single coils.

[ThreeChordWonder]

I don't have that problem the pups are already grounded before the covers. P-90's are single coils.

Yes, I know that...

[JMP/HBE]

Yes, I know that...

IDK if you do as i have humbuckers and you have singles. Not like im going to have your single coil P-90 issues.
Apples & oranges.
I had a SD P-90 in LP Jr and it was one of the best rock tones i ever had.
As long as you're playing with the volume pot turned up you won't even notice noise.

[JMP/HBE]

[Frater106]

Well after a long day at work i wasn't going to mess with putting the covers on as they got here today but i did anyway and after some engineering and some persuasion it worked out good.
Everything sounded good thru the practice amp have to see what high gain amp sounds tomorrow.

That looks so much better! A Custom really deserves pickup covers, as far as I’m concerned-especially a three pickup Black Beauty. An exception can be made for the bridge pickup on a Standard-for that Jimmy Page look/sound.

[ArtieToo]

Well after a long day at work i wasn't going to mess with putting the covers on as they got here today but i did anyway and after some engineering and some persuasion it worked out good.

Yup. Looks great.

[eclecticsynergy]

Really does look good. Now I'm thinking I might need to cover the Distortion set in my own Greco; it's a '77.
Might need relic covers for this one though - the gold plating is pretty well worn after all these years.