Diameter at bottom of base - 15.5 inches. Diameter in middle - 3.25 inches. I can't be sure and can't get a firm date, but these are manufactured in either the 60's or 70's and came from a collection of high-end authentic vintage furniture 15 years ago. I've trawled the Internet and can't find any examples even similar so they're certainly rare. Generally in very clean cosmetic condition.
A couple of dings but they're easily rectified due to the soft aluminium material. These will make a beautiful pair of tables with the right wood or glass top. The item "Set of 2 Vintage Retro 60's/70's Tulip Hourglass Aluminium Coffee Table Bases" is in sale since Monday, February 17, 2020. This item is in the category "Antiques\Antique Furniture\Tables\20th Century".
The seller is "hfluxe" and is located in Nottingham. This item can't be shipped, the buyer must pick up the item.