Here’s my setup. It’s single color for under cabinet lighting when I do my kitchen, but you could snip it to any length and get a smaller power supply to fit whatever needs you have. Or, use a 12V wall wart like in the video.
From left to right: the power cord off the coffee maker my dad had for a couple of decades that died shortly after he did, a 120V to 12V 2A power supply, random red and black wires, a 12V dimmer, a 5 meter roll of warm white LEDs. All from aliexpress.com for around $12 (with appropriately sized wall clips that aren’t pictured.) It all screws together easily.
I’m going to clip off some of the end and use a couple of these:
for completing other LED projects. Maybe edge lit sign for in my car or a light inside of our medicine cabinet or something. They’re super cheap. And, I can have a strobe party in my medicine cabinet. Possibly bad idea, I suppose.
I’m going to cover the dimmer with something attractive made on my Glowforge.