I would start with http://www.keyboard-layout-editor.com/ to generate a layout that you want. Then there are a few tools [0] to take that layout and generate a plate based off that layout. You can then either 3d print, or laser cut it yourself, or send it off a shop to do it for you.
I don't know PCB design, so I think handwiring is the best bet for a first build. QMK has a handwire [1] guide, and I also use them for the microcontroller software.
Though for the build I'm working on now, I wanted a few extra features that would be hard to do purely handwiring (per-key RGB LED and hotswap), so I use a PCB designed to hold a single key [2]. It allows me to do custom layouts without learning PCB design, but it is a lot more work than handwiring. You would still have to build the matrix yourself like a handwire.
If you want to get into PCB design, https://github.com/ergogen/ergogen is a fantastic tool to get you started. I designed my first custom keyboard with it, going in with no knowledge of PCB design.
I don't know PCB design, so I think handwiring is the best bet for a first build. QMK has a handwire [1] guide, and I also use them for the microcontroller software.
Though for the build I'm working on now, I wanted a few extra features that would be hard to do purely handwiring (per-key RGB LED and hotswap), so I use a PCB designed to hold a single key [2]. It allows me to do custom layouts without learning PCB design, but it is a lot more work than handwiring. You would still have to build the matrix yourself like a handwire.
[0] https://kbplate.ai03.com/
[1] https://docs.qmk.fm/#/hand_wire?id=hand-wiring-guide
[2] https://deskthority.net/viewtopic.php?f=7&t=11420&start=