Hi Moyock --
Thank you for asking how others store and display their 3c material -- as beyond the cosmetics -- the subject has important implications to the care and preservation of the stamps themselves.
Back in the late 1980's -- when I first started to specialize in the 1851 - 1857 3c issues -- I had some horrible experiences with my 3c stamps becoming badly sulphuretted with many of the commercially manufactured stock sheets and approval cards that are on the market. I tried all of the supposedly "archival" brands -- Lighthouse Vario's, Lindner, SAFE, etc., etc. -- and with all of them -- within 6 months of storage -- I noticed that my stamps were sulphuretting. I am not a scientist -- but after doing some research, I am of the belief that the various plastics used in these products were the culprit.
Long story short -- the only mounting pages that I currently use for everything I own are Hagner pages. They are advertised to be manufactured using only PH neutral card stock and 100% clear polyester foil. My very general understanding is that products like Mylar and Melinex are simply brand names for 100% pure polyester (although, admittedly, I might be wrong on this). In any event, although by no means scientific -- I can say that I have NEVER had an 1851 - 1857 3c stamp (or any other stamp for that matter) sulphurette on a Hagner page -- and I have had many of my stamps mounted on these pages over a period of almost 30 years.
Here are links to a couple of articles about stamps and plastics that you may find interesting:
https://stampsmarter.org/Learning/S...tics1of2.pdfhttps://stampsmarter.org/Learning/S...tics2of2.pdfAs far as the display goes -- I find Hagners flexible enough to suit all of my needs. They come in 1-row through 8-row formats -- and there is even a specialty format with 3 different sized rows -- enabling the display of singles, blocks, and covers all on the same page. Below are 5 sample pages from my collection -- all as follows -- 1 from my 3c plate reconstructions, 1 from my color chart, 1 from my plating duplicates stock book, and 2 from a small exhibit I put together after the passing of my plating mentor (Dick Celler -- who I miss every day).
I also use 2 row and 3 row Hagners for basic cover displays -- and even 1 row Hagners for the occasional oversized cover. For stamps I want to house on a standard sized approval card -- I simply use a paper cutter to cut down 6 row Hagners to the standard approval card size -- and I order Melinex cover sleeves from Atlantic Protective pouches in which to insert the approval cards. Years ago, I spoke to Hagner about manufacturing standard size approval cards -- both 1 row and 2 row -- but they required a minimum order of 10,0000 cards -- which was just too much for me to handle.
In any case -- a sampling of my collection -- all mounted on Hagner pages -- is below.
Regards // ioagoa
PS -- Thanks again to Don for hosting these large files on StampSmarter which enabled me to show them here.
First up -- here is a page from my 3c 1851 imperforate plate reconstructions:

Next is a page from my color collection:

Here is a sample page from my stock book of plating duplicates:

And lastly -- 2 pages of a small collection of the 1c blues of 1851 - 1857 -- showing an example from each of the plates that produced these stamps:

