Flat spool holder

https://www.youtube.com/watch?v=Inva7H_zTSk
https://www.youtube.com/watch?v=xG6K3lbJHco

Spool holder 7 is glued.

http://www.ebay.es/itm/1500-Umarex-Stahl-BBS-4-5-mm-Stahlkugeln-Stahlrundkugeln-fur-Luftpistole/400766227075?hash=item5d4f875283:g:AkcAAOxyFiRR2GSV

https://www.amazon.es/gp/product/B01EIYJ1U8/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

M8 screw and 2 nuts.
Rubbery pad for the top, I used an old computer mousepad.