A bunch of plastic channels. The five in the middle have been mostly cleaned, but the rest are grimy at the bottom of the channel https://digipres.club/system/media_attachments/files/112/033/303/162/802/480/original/abe60eeb6bfedbf6.png
This is going to take forever to clean. I basically can only clean one channel at once with a cotten bud, and even that is tricky