There are a lot of good answers already, telling how to preserve the original piece of ephemera, and how to make a digital images of each piece. My answer relates mainly to the way it could be recorded in a database, linked to family members and retrieved.
Firstly, you need to know where the original piece will be located; where exactly will you locate that picture / certificate / brooch / cup / hat pin etc. It doesn't matter where you locate it just so long as you'll be able to find it in the same place every time. Using the analogy of a paper file, if it is always stored in a cabinet in a folder 79/12/a, that's where it must be returned after each person has examined it.
Secondly, you need to create the digital file. This digital file can have any filename; it's not important what the filename is, only that it will not be changed later. In the same way that web pages cannot be found if they are renamed it will be impossible to use a computer to find a file if you rename it without telling your computer what and where the new name is. Once you have the digital file it may be far less important where the original item resides - that becomes a matter for a physical storage and retrieval.
Next you need to record information about the file and the piece of ephemera in a database. I created XY Family Tree precisely so that it works as a database. Using XY Family Tree (it's free) you can record information about your ephemera using text and keywords and link the piece to any, or many, individuals in your family tree. Taking an example a newspaper cutting, you could create an image of the piece as a jpg file named "item 44 newspaper cutting 1888 09 23.jpg" (The original piece being filed as item 44). In XY Family Tree you would link a person to this file. In doing so you would describe the piece and you would describe the connection to the piece. The piece could be described thus: "a cutting from The Times, September 23, 1888, showing the opening ceremony for the fire station at Sometown". The personal connection to the file could be described: "John is the 3rd from left in the photograph. He was only 14 years old in the picture but later became head of the fire service." If there was another person in the photograph she could be ascribed: "Edith, mother of John, is the person with the large hat, stood in the middle.". Using the search features available in XY Family Tree it is then possible to find a link to the ephemera by searching for any of the words in its description: "cutting / 1888 / the times / fire station / sometown". Once found, you can see all those linked to that piece, here John and Edith. Or you might be looking at John's information and see the link to the ephemera, which would also link to Edith.
The example material included with XY Family Tree uses a movie file of a spinning top to link two brothers, Lorenzo and Giuliano. This can be seen at http://xyfamilytree.com/help/search-in-notes-attached-to-sources/
The spinning top is the ephemeral piece.
How do you share this ephemera physically? I think the only way to allow physical access to the actual item is to curate it in a museum or safe physical storage. Really, that's down to you how you can manage access to the original piece.
How do you share this ephemera digitally? XY Family Tree has a feature that zips all files in a family folder into a single XYXchange file. This is simply a zip file containing all the digital material for a family and the XYXchange file can be emailed to anyone else with XY Family Tree and imported. You can share it with as many people as you like in this way without it requiring to be displayed on the Internet.