Reducing noise during run with box enclosure

[routercnc]

Absorption depends on the area of reflecting surfaces covered, in a reasonably linear way, so don't waste material trying to cover the Z axis as it is tiny in comparison. You need to cover a reasonable area of the inside walls of the enclosure as per your initial post.

How much you choose depends on your pockets as the costs do add up, but somewhere around 80% of the side and back walls should make a big difference. If you do the roof as well then it will be even better, but secure it really well as you don't want it falling onto the machine.

The acrylic view panel will be reflective but there is not much you can do about that.

Don't know the size of extraction pipe, but the flanges for 100mm are quite cheap (£2.75 ea) - use one on the inside and one on the outside with silicon sealant under the flange for a sealed pass-through:
http://www.ebay.co.uk/itm/like/18154...f14=108&ff19=0