I just used pegs to hold the template in place, and just cut it out. I made the template out of paper, based on the dimensions of the roll, and just tweaked it. Still a little crooked, but it's close enough...
I then used some Popsicle sticks to hold it while it dried. These happen to be bowed in the middle, so it helps hold the centre together - bowed sides in, hold with pegs.
Some paint, then Mod Podge. Don't forget to paint the windows and a door! Add the doorknob once the sealer dries...
This piece just happened go fit perfectly into the top, but the circle works also, or a pod?
I also put a Caffitaly pod in the base, to hide all the inside bits, but it doesn't fit the smaller roll, so I used another pod piece.