MF Box Section Advice

[skeltonmfc]

Hi Everyone

Im after a bit of advice on the best way to build a box section to hide some ducting best place to fix it what material MF or timber. Below is a quick picture to show what im trying to achieve any advice would be greatly appreciated

 

[Deluks]

Fix some blocks (joist offcuts) to a length of 6x1, fix the back of the 6x1 to the web of the steel with blobs of adhesive/tek screws.

Could the duct not be moved inside the steel so it won't stick out as much?

 

[Deluks]

If the plasterboard hasn't gone on yet you could fix through the steel using regular nut/bolt.