I love chopping boards, they are so handy for so many uses.
Here I'm using one under the CPAP machine so it is not sitting on the carpet, and a larger one to form a "shelf" above the machine to help block the noise.
The big board is simply slid in between the mattress and base, it is actually quite solid and can hold a bit of weight.
I can easily disconnect the hose and slide the machine out on the chopping board so I can refill the humidifier tank, clean and replace the filters, or take out the SD card to download my data.
Then I just slide the whole thing back in beside the bedside chest of drawers, easy as.
The towel is for noise blocking, and will be handy if ever I spill water when filling or removing the humidifier tank.
The cushion also helps block noise, but is there more because it is handy to grab in the night for when my bulging disc/back pain becomes too much for me.. I put it under my "top" knee when lying on my side, by lifting the knee height it takes pressure off the disc by untwisting my spine.
The response on waking this morning from wife was... "that was so much quieter." as she snuggled in for a cuddle before we got up for a lazy Sunday morning breakfast.
Overall the unorthodox idea has worked very well.