Typically no. If you have a reputable company(dreambig by Ray and pslate custom are often recommended) you’re “probably” ok safety wise.

But they usually cost a fair bit for good quality.

I’ve never made my own(i dont trust myself) and just rely on my cabling skill to hide things away… On some occasions my efforts have been less successful than others but I got better and the only cost was my free time.

I have done, no so much as made but cut down sata power cables to fit, wouldn’t recommend fucking with the more vital cables

I got mine from pslate, 10/10 would buy again. Shipping to Europe was my only issue, apparently USPS sucks ;)

Not sure what you mean by “worth” here, it’s a bit of tedious work, the other day I stumbled on an YT comment response saying author spent around 8 hours making a motherboard 24pin cable, I’d say it’s worth it if you absolutely need it, dude’s cables were perfect length and shape tho

dreambigbyray on etsy’s cables have been going strong for me in my ncase for about 3 years now. it makes cable management so much easier when theyre appropriately sized imo. l