nice description!

2 years ago I setup such a machine with following parts list. MikroTik WLAN cards are superior since running Atheros chipsets. Feel free to include parts in your documentation.

1 x PC Engines apu2d4
1 x PC Engines case1d2blku
1 x PC Engines ac12veur2
1 x mSATA mini PCIE 8gb
1 x MikroTik R11E-2HPnD, miniPCI-e card
1 x MikroTik R11E-5HACD, miniPCI-e card
4 x Delock 88395 WLAN 802.11 ac/a/b/g/n 2 dBi
4 x RP-SMA Jack Pigtail to MMCX (18cm)

seller I bought everything from: varia-store.com