I've used Cedarsmith compressed shafts for more than 20 years. They're good shafts. He runs a 23/64 shaft through a die to compress it to 11/32, or 11/32 to 5/16. That process compresses and burnishes the outside of the shaft, but the internal fibers aren't compressed very much if at all. The burnishing makes the shafts less permeable to stains. Going with this type of shaft has enabled me to get the heavier spine and physical weight of the 23/64 shaft in an 11/32 diameter.
These shafts of course are not like Sweetland compressed shafts, which are no longer made. Sweetland compressed cedar planks under heat and then doweled the shafts from the square stock cut from the compressed planks. This process compressed the cedar throughout and enabled him to get even heavier spined and weight shafts, stronger too.