Make a USB drive read only

My best option is use DISKPART form windows

DISKPART

LIST DISK (To check which flash drive listed as disk in windows)

SELECT DISK 1 (It should be disk 1 if you have single hardisk attached to computer, disks naming starts from 0 but partition starts from 1)

ATTRIBUTES DISK SET READONLY [And its done ;-) ]

Any locking mechanism I'm aware of would be on your local machine.

Burn DVD's of the important stuff... :) That's about the only thing that will ensure they are read-only.

You might want to look at giving them a web interface via some apache file-sharing type of software. That would give them some sort of web-nas view and you could more easily lock down the writes...

What about checking the "Read-only" box in the main folder's Properties and then applying to all subfolders?