When I planned these beds I spaced them far enough apart to get my lawn tractor in-between them, but getting between them and the fence involved my weed whacker. As anyone with a fence has found out, maintaining the grass at the base of a fence is a pain.
I'm 3/4 of the way done with the edging. It's 10" tall with something like 6" or 7" of it buried. It does a good job of keeping grass out of our other beds, so I'm sure it will do a good job here. The downside is the most effective way of installing it is to trench first, put the edging in, and then refill the trench. If you try to use one of those big pizza peel looking things to make a narrow slide the will usually get wavy due to variation in trench depth.
I mowed to basically ground height between the beds, weed whacked around the beds, and put in a layer of that thick paper builders will use to protect flooring below the mulch. Some areas for cardboard instead, but we just didn't have enough cardboard to cover it all. Hopefully it will be enough to kill the grass and hopefully that results in less grass appearing in my raised beds.
I hope you're back to your normal physical self soon.
As far as the 3D printer goes, there are three main types of categories of people with printers at home:
If you're modeling it will be mouse and keyboard, but a SpaceMouse will improve ergonomics. All you're really using the keyboard for is number input.
If you find yourself in the functional print crew, don't be surprised if you wind up printing things to help in your garden. Some of the PVC fittings holding together my arch are now printed parts (less effort to model and print a replacement than drive to the store) and the hooks the "gates" to my fence hang on are also printed. Once you get in the habit of finding things you can print you'll be finding them everywhere.