Forum Moderators: open
"We sell new and used toy buildingblocks building blocks playblocks from blockmanu1, blockmanu2, blockmanu3 in grey, gray, blue, and red colors."
It's the keywords in the OFF page spots (inbound link text and other text on that linking page) that means the most these days. If you can, that's where I would focus on getting all the variations.
Then on each page of your site, you have a new opportunity to use the meta tag to create a new variant of your description -- one that interests the targeted visitor in clicking through.
It's a question of balance. If you try to do everything at once, than you actually end up weakening your over-all position.
As Tedster indicates, this is what is seen by searchers so it should be crafted with them in mind.
Currently, the relative importance of the meta description tag is so low that it is truly best used to present a compelling and action oriented description.
Also, in the case of Google, which actually compiles the description for its SERPS by taking the sentence that encapsulates the search word from within the body of the page you can use the meta tag to generate clicks.
Also, to rank well for the specific manufacturers, you should have a page specific to each of the manufacturers. I would focus on making the description for those pages as precise to that page as possible - for example:
"Offering a large selection of <most popular keyword variation of their type of blocks> from blockmanu2 in all shapes and colors"
This way when you actually rank well, it will capture their attention and prompt the click.
>>"We sell new and used toy buildingblocks building blocks playblocks from blockmanu1, blockmanu2, blockmanu3 in grey, gray, blue, and red colors."
"Building blocks both new and used from blockmanu1, blockmanu2 and blockmanu3. Blockstore, your premier online source for play blocks, carries buildingblocks in your choice of gray, blue and red."
That way you're grabbing in an occurence of the "you" word and also inserting a little branding for the site.