Hypex FA122 - backbox recommendations - ?

Hello.

Posted this query to TechTalk forums also. My only goal being to gather collective wisdom closest to its' source.

Basics: I'm trying to get a clear picture of production costs on a 2-way active enclosure using a Hypex FA122 plate amp. Guessing that some of you folks have had to address the lack of readymade backboxes for FAxxx series already. If so... please share your UL94 VO+V1 solutions here.

Sidenote: Been lurking these forums for a couple years now. Longtime installer, but still new to hardware design.

TIA.

Brian