Started out by not wanting to blacken my good honeycomb table I use for acrylic by cutting craftwood and and other stuff on it.
Several months ago, the radiator in my wagon blew one of the tanks off the end and had to be replaced. I was about to take it to the dump when I noticed the similarity of the structure to my honeycomb table.
The rest was simple.......

Step 1:

Make sure you are using an aluminium radiator
Mark to length and cut the radiator using an old timber saw.

Step 2: Done

Side by side....
In the machine.....
Took all of 10 minutes.
The only change I would make is to pressure wash it before cutting, less messy.
Small update - Gaffer Taped the raw edges.

24/6
Tips.
When working with thin plywood, I have found that I can flatten the sheet by planning several points in void areas about 2 mm dia on a different layer in the software. Cut this layer first and pause the laser to screw the sheet down to the radiator. The two flanges which were left are convenient for clamping the edges of the sheet flat using small bulldog clips from the stationary supplier.