Thanks to a tweet by a E. S. Ringwald we can now see a group of GFs
in the wild!! (Does a group of GFs
have a designation?)

A glimmering of GF? A conflagration?
Looks like a Glowtwentyfourge to me.
A glimmer!
A flash?
A collation?
An Inferno 
Three or more Glowforges are a glory of Glowforges or a fury of 'forges.
A bonfire of 'forges?
'Tis a rare sight, indeed, to see a Pulsar of Glowforges in the wild. They are skitterish creatures, easily frightened by sudden movement. If you approach too quickly, they will scatter and hide; in some cases they will not reemerge for a year or more.
Danged if you guys/gals haven’t come up with all the cool names already. 
A flurry of forges? A gaggle of glows? 
A foundry of 'forges!
Edit: Although, looking up the etymology of foundry, it might be better to say “a fondre of 'forges”. 
If it is a murder of crows, perhaps it is an annihilate of lasers?
A unicorn is a fabled creature impossible to capture.
The Glowforge is a fabled creature impossible to capture.
A group of Unicorns is called a blessing.
I’d say group of Glowforges is most certainly a blessing.
A week’s production?
Looks like a Legion of Forges as they are many.
A forgery? Otherwise a 69x20 continuous cutting area?
Wait, wait…I got it…a frisson of forges. 
I believe the obviously correct term is a surfeit.

