Is there an elegant way to build a round window with the Radial Cockpit Window? I've tried experimenting with vertical clip plates but it just ends up looking odd.
The 2x2 plus 1x1 round plates should just fit within the arches of the arch bricks and provide just enough friction to hold:
If stability is a bigger concern, replace one of the 1x1 round plates with a 2x2 plate in trans-clear. This should keep the window from wiggling:
There should be enough room inside the 1x4 arch brick to snugly accommodate the 2x2 plate:
Bear in mind that the curve of the inverted 1x2 arches is not the same as the 1x4 arch, and there'll be a small (about 1/10th of a stud) gap between the inverted arches and the 2x2 dish: