For those that are interested here are some photo's that show typical silencer construction for an air rifle.
You will notice scouring type pads are cut to baffle shape, this is used to help slow down the on rush of air and are usually placed between baffles, felt also has been used.
Other designs have perforated center tubes wrapped with these pads or felt enclosed in an outer tube.
Plain flat or M type baffles can also be employed the M type being best, it should be noted that unlike a silencer for a .22 rimfire the baffles for an air rifle should not be placed an equal distance apart ( or mutiples , for instance if your first spacer is 1/4 inch do not make the second spacer 1/4 or 1/2 inch or 3/4 inch, better something like .3 spacing and the next .7 and the next .4 ) for better disruption of the sudden air flow.
Also unlike a rimfire baffles may be made from sturdy plastics, many different objects have been used for baffle with success, such as coasters for the bottom of chair legs, plumbing parts, rubber or metal washers, etc. you are only limited by your imagination.
You can also obtain good information by visiting English airgun forums which you can find on line.
The usual disclaimer applies in regards that these are silencers and require the $200.00 tax stamp unless pinned and welded to the airgun barrel and cannot be removed and placed on a firearm.