Multiboard beam top layer alternative

Someone on reddit asked why there was not much holding together the top of a multiboard container made with beams. I've used beams on top instead of just the corner pieces before, but why sacrifice space on that top opening.

Lacking most of the design elements of the genuine beams, these are made for a very specific size, I'm too stupid to parametric.

Suggest lite clips in the end of the long bars, full clips might split the layers.

I thought 0.2mm gap on the end of the long bars would be a good idea, the gap came out to 1mm on mine so dropped that to 0 and uploaded.

I can generate some other sizes if there's one you'd like.

The 4x8 and 4x4 ones I later added are a bit different, obviously the 4x8 is a single piece, should just fit on a 245x245mm bed. The 4x4 joins together differently, the clip to join the ends is over one of the tile clip holes unlike the original ones I uploaded with .5 lengths to put the join between 2 tile holes.