ABSOLUTELY! I'll take some reasonable number of them, but that's up to you and what the replies add up to from here on in. I keep a lot of 'spare' flies in my tying drawers and bins and right now they are in flyboxes that I could be using in my vest or chestpack. I could swap out the off-season or other fishery flies into these and free up those smaller boxes. On second thought these dimensions would fit into the rear compartment of my chest pack as well, definitely in my backpack, etc.
They sell sheets of flyfoam w/ adhesive backs. I can't remember where I saw them last but I bought some to line other boxes I've adapted. Probably Hunter's Angling Supplies or Blue Northern, I will check.