Counter top extension
We had a kitchen table that you could increase its surface by pulling out extensions on both long sides. These sat just under to top and pulled out and up to set even with the top. Is such a thing still available? Are there instructions on how to make one?
Re: Counter top extension
Personally,I don't think this would be a great solution for your kitchen countertop. I have one of those tables you've described with the sliding leaves. The principle behind this is that the top has to stay loosely connected to the base and this allows the leaves to slide in and out. It wouldn't be a very solid top for the countertop. I guess it depends on preference but I like my kitchen counters to be solid, not rattling and loose.
You could look at the option of putting in a leaf that would simply slide out and end up 3/4" or so below the counter. Everything would be solid and versatile.
Just an opinion.