DIY "vacuum" plunger food storage jar ?

I have been researching the different kinds of food storage jars which reduce the amount of contact oxygen has with the contents of the jar, I found the a manual plunger style from Prepara to be the most simple, over their mechanical rivals, which use a levers or other intricate mechanisms.

It's such a clever design, but since their launch demand has decreased to the point that they've begun thinning the glass containers, and now their slogan reads that only food safe BPA-free plastic touches the food (rather than only glass and food grade stainless steel), which I have a problem with, along with the prices and the fact that the one way valve mechanism cannot be deconstructed to be cleaned..

Prepare food plunger: 

I would therefore like to make my own, how hard can it be? I would like to use a Weck jar (because of it's strait sides and all glass design) and just push down a plunger with a food grade silicone flange to achieve a seal, one that can easily be cleaned, does anybody know of a DIY tutorial for this ?