With all the components and circuit schematic finalized, I gave [MaazMobin] a crudely drawn schematic with components and my preferred pin numbers and asked him to design a PCB in EagleCAD.

He did so, then we sat together to finalize the component positions and then routing was done and finally SEEED Studio Fusion PCB Service was used to get the PCBs fabricated.

Maaz was good enough to put it on Github - https://github.com/maazmobin/pi_hat_eagle - this was his and mine first experience trying to make a PiHat with official dimensions and sizing.

I forked the repo and did some final modifications, mainly cosmetic wise, silk screen and other things.

https://github.com/zaidpirwani/pi_hat_eagle