I did 1.5 inch. I’ll post pics but for the tapper hole I used 1.5 pvc pipe, wrapped it in clear packing tape and used silicone to attach it to my form. Once it cured and before I sealed it I used the tapper template that came with the kit and used a concrete drill bit too drill the holes. It went right through it. As for the arm rest… I thought about using one but ultimately decided against it.
Good luck…