Now, I'm just playing Devil's Advocate here, Dirge...
Except... no amount of acrylic casing is going to prevent the plastic from deteriorating over time.
Very little from the eighties is sufficiently rare enough to warrant this sort of treatment. For instance... I think we can agree that we would call a MISB 1984 PEPSI Optimus Prime a rare Transformer. However, there are currently 36 of them grade, with 34 of them being over AFA 75.
By comparison, the ENTIRE 1979 line of Mego SuperHeroes only has 24 MOSC graded figures. You might have to trust me on this, but I can tell you that Mego fans are just as rabid as Transformer fans. And unlike say, the Action Masters line, its not due to the lack of value that they're not AFA'ed.... it's due to lack of supply. (Though, I must admit there's also a tendency to not want to AFA Megos because of the plastic deterioration issue).
Sometime in the early 80s, our society changed to a consumer/hoarder culture. They made more. We bought more. We saved more. I think society took all those 1970s, "Indian-Crying-whilst-floating-down-the-river-with-no-paddle Don't Pollute" ads to heart, and just stopped throwing things away. (Though, I assume you didn't get those on your side of the pond, eh? Here's a link: http://www.youtube.com/watch?v=j7OHG7tHrNM
Our stuff's just not THAT rare.
Not to mention, once cased, you'll lose ALL tactile appreciation for it. Here's an experiment to try:
1) Find a clear box.
2) Find something you appreciate to put into clear box.
3) Note how you feel while looking at said object while inspecting it (IN YOUR HANDS!) before putting it into the clear box.
4) Put item in clear box.
5) Note how you feel while looking at said object in its new clear boxy home.
6) Any difference?
even if it is * only * a toy that their great grandfather once played with
If it's AFA'ed MOSC, then how did Great Grandpa play with it?
If you're simply trying to pass on something you love, you could just as well wrap it in archival paper, a few paper bags, and some bubble wrap, and a plastic tote. Or seal it in a vacuumed environment.
And be sure that you have a loose one as well, so the conversation can be more touching:
: "GreatPa, wot's this?"
The Consciousness of Dirge, Uploaded onto the Family's Pentium X Braincore with Windows2urSoul 2089
: "Why, That's my prized Action Master Soundwave toy, that I loved dearly, Johnny!"
: "Cool! (Starts opening the case)"
: "Noooo! Don't open it!"
GG: "Errr... but why, GreatPa?"
: "There's only 35 of those left in existence. I'm trying to preserve my childhood memories for generations to come, so that you can understand what a real, honest to goodness toy that people played with and loved was like in the future! Now, you kids are spoiled with your Holographic Virtual Worlds and Neural Jack Virtual Toys"
: "I see... but how did you love it and play with it, its sealed in this case, in its original packaging?"
(This is where you need to whip out the beaten, playworn, loved on version. Umm... but don't love on it too much. That's gross.)
Or something. I think I started rambling (about 45 sentences ago?)