Some questions ...
Do you want to use the existing Max moulding? If so how deep is it?
Have you mounted any of the items or are they still in original condition and is method still an open issue?
What are they made of? How large? Heavy?
Can you post a photo of the collection?
Quantity? Size? How much space being left for additions?
Does the client just want the corkscrews or is he/she up for an 'arty vignette' using additional items/images?
Are there price constraints? If so what are they?
Dependent on answers, you could consider anything from a simple removable back, to a slider, to a hinged front, or maybe a gravity groove, or maybe something else altogether (maybe not even a 'frame' per se - for example I have half an idea using cut off wine bottles for a really wicked display!)
Many options for creating adjustable mounts/holders/supports ...so much depends on specifics