I am not a wood worker - hopefully one of them will drop in. I am wondering if a Dremmel would work. It would be a much slower process but it is a "gentler" cut than a saws-all. Cut the opening as small as possible so if there is any chipping , it would be covered by the trim of the tube.

Of course I would say use a practice piece of wood first.

Good luck!!

The installers aren’t carpenters though. It’s actually the sun tunnel company we asked about what would be best - install the cedar liners before or after the sun tunnel installation. They said either way is fine🤷🏻‍♀️

Millworkman is correct, it’s the skills that are lacking. Finer blade on a jigsaw, masking tape, and much more care.

Make an MDF hole jig just a little larger than the hole size you want and tack it to the cedar. With a collar on a plunge router with a 1/2" double fluted straight bit, plunge cut the hole. No chips and a perfect circle.14:34.

I would use an oscillating tool by making plunge cuts around the circumference of the desired hole.

Joseph is correct and those hacks need to go back to whatever place they trained for refresh .