Well, I basically cut wood sticks with rectangular profile at roughly the same size as the dog bed. I also cut the cheapest wood sheets I found as stripes. Then I screwed them together. See pictures below. But try to find type of wood, which is as stiff as possible. These pieces bend easily under the dog's weight! Worst of all if the wood touches the floor, your readings will be inaccurate. I think that also the bending messes up with the load sensors' "measurements". Also, leave enough space at the center for the controller board (see later steps).

(currently there is an issue with image upload)

It was possible to use female pins to insert all necessary components. If you scale is lower/slimmer, then you may not be able to use female pins, perhaps even have to design a PCB.

First I did not have padding underneath the load sensors, which was not good for the floor. Plastics padding alone don't go well either due to low friction. I guess, that's why commercial scales have some sort of rubber underneath. I do that with hot glue in my projects.

In my case, the scale was too large for and the cables too short. I cut all 12 cables and inserted (soldered) an extension (same length everywhere) and protected with shrink tubes.

with wood screws

I made a cable with JST connector to connect the display to the perf board.

basically, insert the perf board (with the components) into the enclosure, route the cables and screw the lid.