Today I started my Hackpad macropad. I followed the Hack Club guide and built a simple 3-key version first, so I can learn each tool before adding a knob or LEDs.
What I did

Installed KiCad on Linux as an AppImage and made a launcher for it.
Added the Hack Club symbol and footprint libraries (XIAO and SK6812) to KiCad.
Drew the schematic: a Seeed XIAO and three switches, each wired to one pin (D10, D9 and D8) and to GND.
Assigned footprints: MX switch footprints for the three keys, and the XIAO footprint from the Hack Club library.
Opened the PCB editor, imported the parts, flipped the XIAO to the back, and spaced the switches 19.05 mm apart.
Routed all the traces and joined the ground connections.
Drew the board outline on Edge.Cuts, which came out at 65 × 64 mm.
Ran the Design Rules Checker until it showed 0 violations and nothing left unconnected.
Started the case in Onshape, so I can export a STEP file.

What went wrong

KiCad has separate library managers for symbols, footprints and design blocks, and at first I added the footprints to the wrong one. The XIAO footprint didn’t appear until I fixed that.
The checker kept reporting a missing GND connection. I had two ground wires that crossed but didn’t touch. Joining them on the back layer fixed it.
The board outline was missing until I drew it, which gave a “malformed outline” error.

What I learned

A schematic defines the connections, and the PCB is where those connections become physical copper.
The thin blue lines (ratsnest) show where a wire is still missing.
The checker is useful for finding mistakes you can’t see by eye.

Next

Finish the case in Onshape (base, switch plate, USB cutout).
Set up the firmware.
Put everything in a GitHub repo with a README and a bill of materials.