1 inch minimum. Most poolplayers will agree that the thicker the slate, the more consistent the table will be. That is why experienced poolplayers that can both afford it and have a room to support it, will have a table with 1.5 inch, and even 2 inch slate. However, most tables are 1 inch slate and most poolplayers would agree that they cannot tell the difference from 1 inch to 1.5 inch. Thinner tables are made, and most will argue that you can tell the difference.
The first difference is cost, as slate tables cost more. The second difference is weight, as a slate table weighs more than non-slate. The third difference is "playability". A non-slate table and a slate table that has less than one inch slate will not provide the same tolerances and ball reactions as compared to a quality one inch slate table. This third item is the reason all regulation pool tables are required to have one inch slate.
10mm
This is a subjective answer - the important thing is to get a quality table and get it set up by a qualified professional. Any table sold with 1.5 inch slate you can be certain is a well manufactured table. However, the much more common 1 inch slate tables you generally are getting what you pay for. Although Brunswick is the biggest name in pool tables, you can get a high end table from another that costs less and is just as good as the Brunswick.
about 4 inches thick
plank
I like my oatmeal thick, with fresh berries on top.
Placing the cords and wires away from the table so that there is safety from the feet of the operator and also have a thick table to separate the two.
any of the metalloids. find a periodic table. there should be a thick line that looks like a set of stairs towards the right side of the table. any element along that line is a metalloid.
Depending on how comfortable you are using a table saw, you can do it free hand or with the miter gauge. Use a 6 inch piece of 2x6 and run it through at an angle. Usually about 1/4 inch thick on the thick end.
If what you are looking for is a thick pad that will cover your entire table, and will remain in place for long periods of time, you want a Table Pad. There is a web site -- Superiortablepad.com. There are others like it. Basically, you make a paper template of your table and they make a custom pad that is in several interlocking pieces that is about one inch thick. Expensive, effective and very much worth it if you eat on your dining table a lot.
Slate is a fine-grained metamorphic rock made up of clay and volcanic ash, while flagstone is a sedimentary rock that is split into layers for use as paving material. Slate tends to have a smooth, uniform texture and is often used for roofing, while flagstone is more irregular in shape and is commonly used for landscaping and outdoor patios.
You can always put padding down on your kitchen table or a thick tablecloth to protect it from day-to-day scratches.