Buy a length of 24" sonotube (cardboard concrete form), split it up the back and snap it around the sun tunnels. Maybe 18" would fit, or go crazy and use 36"d. sonotube. (?)
Hard part is scribing it to the slope of the roof.
Casey

Casey, that is a very creative idea. Thanks! DH wonders how challenging it would be to open up and successfully wrap around the sun tunnel. Have you tried this?

Carol

You'd have to buy a length and try it ... at worst, slice it in half and tape it on.

If you framed with 2x2s and 1/2 plywood it would be less bulky. You could be a bit more creative: hexagons and octagons would hug the contours better and aren't that hard to do ... again, the tricky part will be the roofline.

Hi Lazygardens,

Thanks for your input. Good point about just slicing the sonotube in half if slicing it up back is not easy to work with. We had thought about hexagons or octogons. We would prefer to round them if possible as they would be safer given they are right in the middle.

Thanks,

Carol

Take some of the sheet polystyrene insulation and cut some kerfs in it so that it's bendable in a circle, then cover it with spray adhesive and rolls of cork. It will make a grand bulletin board for them to hang art and notes and what not.

live_wire_oak,

Thank you for another very creative idea! I certainly like the cork idea.

I keep wondering if I would need anything else for strength in addition to either the polystyrene or sonotube? For example, perhaps I should try to put another layer of ducting material or a plumbing tube over the sun tunnel for added strength before adding the cork. The ducting/tubing for the sun tunnel tubes is rather flimsy.

One contractor suggested the material that Bathroom Fitters used for covering tub/showers might be worth investigating.

Carol

No matter what I think I'd want a frame around it so there would be no chance of bending/knocking anything with some playing inside the frame and once you have that you can wrap them with something you feel would be safer after the tubes are safe from damage.

Lyfia,

Thanks for your comments. I definitely agree that it needs to be strong. I have three boys and a girl. If the structure is flimsy, the kids will crush it in short order. with accidental play. I like your idea of framing the tunnels (perhaps use lumber to build an octagon shape as suggested by lazygardens) and then wrap it with a material to get the rounded shape.

Carol

The cardboard is very flexible, but will keep its shape. If you take a thin rip of plywood and some drywall screws you can "close the incision" when it's in place.
The most creative use of sonotubes was in a clothing store where they cut 36" ones into changing booths with doors cut out and then re-attached, secured to the floor and ceiling somehow; this was in 1978. I was amazed.
Casey

Thanks for the extra ideas, Casey. If a store can use them as changing booths, I would hope they would be strong enough for what my kids might dish out. Any idea how they could be attached to the floor?

Thanks again for this amazing idea.

Carol

They also make wacky board which is like a plywood but extremely flexible and can be bent into curves.

Can you embrace it? Make them strong, 2 stout pillars then finish like trees and hang a hammock.

Three quarter inch plywood, kerfed on a table saw and supported top and bottom on the outside (or inside, but will take up more space and need more kerfed ply to encircle), with either plywood or 2 x routed or band saw cut to a circle .

Wow, the creativity on these boards is amazing. I love all three of the newly posted ideas as well as the ideas posted earlier! I will have a whole list of clever possibilities to present to the carpenter. I wonder if he has ever heard of Wacky board! Glad to know kerfing regular plywood will also work as wacky board may not be available in Canada. The tree/hammock idea is sweat too. Looks like there is more than one good way to solve this problem.

Thanks everyone!