As a start I'll give you the approach I use for working through folders. There are probably varios ways to approach this but I've always used the FileSystemObject. You need to reference "Microsoft Scripting Runtime" first and I have a quick demo below to get you started:
Dim fso As Scripting.FileSystemObject
Dim fdr As Scripting.Folder
Dim fle As Scripting.File
Set fso = New FileSystemObject
Set fdr = fso.GetFolder("C:\")
For Each fle In fdr.Files
Now presumably your next stage is to open each database from code and iterate through the tabledefs collection to haul them in.