Which material is lighter? MDF or Partical?

[JC-ATL]

Yeah, I have a pretty good idea on cost and fabrication for the CF box, just didn't know about the acoustical properties.

[67 Type-1]

MDF is what the pro's use because it doesn't vibrate like plywood does.Plywood is not solid,there are small voids in the layers.MDF is solid and non resonant.The only plywood I have seen used for sub enclosures is made from spruce wood and is quite expensive.Use 3/4" MDF,with possibly a 1" front baffle.Glue all panels togerher before screwing them together or using an air nailer.You may have to use some internal bracing depending on the size of your enclosure.then use silicone caulk on all the inside seams,and the speaker terminal plates.If it is an infinate baffle type of enclosure(sealed box)you can fill it with polly fill,it will fool the speaker into thinking it is in a larger enclosure,it will play lower and help prevent standing waves.Also make sure your enclosure has the correct internal volume for the drivers you are using.This information can usually be found on the speakers spec sheet.

[67 Type-1]

Aren't they the same thing? Both are sawdust glued together. Do you mean OSB (chipboard) I believe that is lighter.

MDF and particle board are not the same material,they don't even resemble each other in a side by side comparison.MDF is solid,when you cut it with a table or jig saw the resulting saw dust is just that.Afine powder like dust.OSB and particle bosrd are pretty much the same thing,with the difference being the size of the wood chips.They are both lighter than MDF.MDF is smooth and dense so as to be non resonant when used in speaker enclosuress.You won't find OSB or particle board being used in any reputable install shops,or in a quality built subwoofer enclosure.
(o\_|_/o)