Hi D

Yes, they are top bee space and as far as I recall with a sufficiently generous top space to allow a runner and a still a bee space above the frames. I should have access to some this afternoon and if I remember I'll measure the space. I can visualise the Correx divider working as you suggest. In that case I would leave a break in the frame runners to make shaping a bee-tight divider easier. It would need to protrude sufficiently above the top bars to meet the roof, and have extensions that sit on the shelf where the frame lugs sit. One other complication is that there is a mesh floor. This is a cut-out piece in the polystyrene and mesh is affixed to the underside. So the Correx would have to be shaped to match the cut-out in the floor too. I can see lots of cardboard attempts before you have a good template for the Correx but it should be possible.

We have 15 to play with and 20 Apideas thanks to Awards for All but if I was paying for them myself I might be tempted to try as you suggest. The one problem might be cutting off the access to the feeder. A frame feeder in a 3-frame nuc isn't really on so you'd be reduced to thin pancakes of fondant for top-up winter feeding.

G.

Here are two boxes, one just acting as a hive stand to support the box into which a swarm was knocked (not our swarm we think!). The entrance is a small slit inside that cut-out.