I just disassambled my WL-HDD
and give you some cira weights (I used our kitchen balance so that means cira )
Case: ~110 grams
PCB: ~ 80 grams
Harddisk ~100 grams
Screws/Frontplate ~50 grams
~ 340 grams
Asus says 200 g, i guess without a Harddisk.
I guess u won't need one for your project.
May be a good idea to cut of some weight is to do without the case and the frontplate.
It means 80 grams are left. Possibly u could use something like a freezer bag. Or something antistatic to get rid of the 110 gram case....
My Asus Collection (just starting):
wl-hdd (220.127.116.11-6a, with HUB, USB-HDD, CARDREADER, CAM) Asus A3878GLP Notebook 15" Centrino 2,0 , 1024MB, 80GB, WLAN built-in, DVD+-RW