Is it worth the effort?
I don't think so
I also believe that it doesn't worth the effort if the only goal is to save some bucks.
If you are into electronics, OK, it can be an interesting (short) project, but if you don't, you may end up breaking some parts and paying more at the end. ("It's hard to solder those without magnification", even the video tells that).
Also keep in mind that a Trezor is nowadays 59 EUR, not 89 EUR, like the (start of the) video shows.
Overall, I liked the idea, I'm going to save the YouTube link and maybe even make it again before the end of this year.
If you want to make sure you'll have it, I advise you save the video (mp4) not the link. It's a more.. future proof option.