Scrying is something I do a lot with in my practice. It's kind of a fundamental part of many folks magical practice, with an incredibly long history. It's really just using a vaguely reflective surface to look through into the spirit world. Apply your trance work techniques to this, call your spirits. That's it, not hard right? Biggest thing I see people stumble with here is what kind of surface to scry into.
There's a few different options that are fairly traditional. Bowls of liquid, especially dark liquids, stones, or things like the black mirror. I like the black mirror because it's easy to put symbols and sigils directly on, and clean right off after. They are though, something that you'd have to order online, or pay a premium for at the local witchy store. So let's just get you to make one.
Some people want you to get a round or oval one so it doesn't have corners. I don't think it's important myself, but I'll put it out there so you're informed. I usually just grab a picture frame from the dollar store for this, although there's no reason this process wouldn't work with any size or quality of picture frame.
This does NOT work with regular paint with a brush, only with spray paint. Matte black is traditional, and what I use. You either want matte black, or as high a gloss as you can find. It's really about which direction works best for you.
Here's how you do this then:
Pull the back off that picture frame, and pop the glass out. Light decoration for the frame is probably alright, but I usually find it better to leave it as plain as I can
Clean both sides of the glass well. Soap and water, then rubbing alcohol. If you use an alcohol based spiritual product like commercially produced Florida Water, that will work for rubbing achohol.
Once that's dried, spray a bit of your spray paint on something else, until you're sure it's flowing right. Note here that spray paint is actually pretty nasty stuff, and it's suggested that you get an activated charcoal filter mask and eye protection and such.
With each pass, you want to start and end off the glass and pass across it, and make sure to overlap your passes. Don't try to be too heavy, you can't afford any runs. Light passes are best.
Let it dry for a couple hours between coats, enough that you're sure it's dry to the touch.
Repeat at least 2 coats, if not 3. Go cross ways to your last coat to keep from lines and uneven paint.
Leave it alone for 24 hours at least. Dry paint hardens or cures over 24 to 48 hours, and it's a lot less prone to chipping after
As long as you put the back on and leave it, you don't really risk scratching that paint, so I never mess with a topcoat for this. Total cost minus the safety gear here is like 10 bucks if that, and in theory you'll use this safety gear again, so hopefully this saves you a few bucks.