If your “sun tunnel” has a piece of glass (or plexiglass), at the lower end, where it lets light through the ceiling, you might consider simply putting some window tint film over it. You can find this in the automotive section of your favorite store, or any auto parts store.

Another option, if you do NOT have any kind of surface to install window film on, would be to use a piece of Lexxan that is already tinted. Most of the ‘big box’ stores, like Lowe’s will carry this, or you can try a marine supply store.

You asked about a horizontal drape — there are shades that are made to go on sunroofs, and skylights, that run in a track, and can be mounted as you need…. but they’re a little on the pricey side… You might want to goto a local junk yard, and see if you can find a vehicle with custome windows, or ‘sun roof’, and use the hardware from those… it would consist of a couple of tracks, and the brackets that get sewn or riveted to the material. Our conversion van has these types of drapes on all the side windows, and the sun roof window.

Have Fun