Used to be that you had to construct an elevator on site with pre fabricated parts in your framing. Now they have self contained units that require only a hole cut where you want to put it. It's about as much work as installing a fabricated spiral stair, but the hole is smaller. Single person use. You can get sizes that will accommodate a wheelchair.
I haven't studied these so IDK about 3 floors. If
look171 goes to the builder's show all the companies will be there. There is usually someone doing a YT on these and all other shows. That's where the latest products are found.
Just a random sample:
