This bullseye window was part of a job in Weybridge we were asked to plaster by one of our old school builders (no dot and dab.  All solid plastering).  We have included it to show the detail involved.

Firstly, we had to find the exact centre of the window.  We did this with our cross line laser.  Once we had the centre, we could then work out the dimensions. 

Next we laid two sheets of ply on the floor, joined them, drew out our circle and carefully cut it out.  Again, using our laser, we were able to fix our ply sheets into the exact spot, we screwed the boards to the wall, but left ourselves ½’’ depth (by placing half inch ply behind the sheets).  The reveal part of the window was then plastered.  Once hardened, we removed the ply and fixed the beads.  Next the wall was plastered.  Finally we set the wall and reveal, leaving clean neat circular window.