A 386 will be worth

or a 8086 motherboard for these guy

most compact 8088/8086 board you've seen?

A question: Does anyone know how the cymbals of the old discs were covered, that the cymbals are brown and what product was used to cover them.

and how they were covered and what product was used to cover the floppy disks

If the magnetic layer is brown (typical for old magnetic media, e.g. 5.25" DD floppy disks), it is most likely be some variant of ferrous oxide, just as it is also used on magnetic audio tapes.