Any ideas for creating a base for a granite top?

have the guys trim around the edge and place on table top ! Looks great

Whatever you use as a base will most likely have to take a lot of weight. Depending on the size of the table top, and the height you want the table to be, you could possibly make a base (stem) using 2 x 4's or 2 x 6's, beveling the sides so they fit tightly together. If necessary you could use metal bands to re-inforce the product you use to fit the boards together. Depending on the size of the table top AND (important here) the height of the table you are thinking about, you possibly will have to also make a large enough round base to afix the "stem" to in order to keep the table stable.

Alternatively you could make a large wooden round and affix legs and bracing to them like most square or rectangular tables. Depending on the size and weight of the granite you would most likely have to use six and possibly more legs that need to be solidly attached to the wooden round, and then braced to keep the legs stable. Look at it like you would a floor lamp vs a table lamp. The higher the lamp and the heavier the shade the more lower stability you will need to keep it upright. A "bar height" table is going to be more difficult to stabilize than say a short end table. Go to some stores and look at how table legs are placed on both rectangle and round tables, then remembr that you are using a table top that will be far heavier and thus need more bracing.

See if this helps.

https://www.hunker.com/12003257/table-bases-that-will-hold-granite

https://tablebases.com/blog/2017/05/choosing-a-table-base-for-a-granite-or-marble-table-top/

https://www.pinterest.com/explore/granite-table-top/

https://www.hunker.com/13404246/how-to-build-a-table-frame-for-granite

I like the idea of a round table - how about a large pillar with 4 feet to keep stable?

If you can find a small but very sturdy pillar, or you can go to the Eversource Department (we used to get them from Public Service Co.,), and ask them for a wire spool. Now these are wooden and are large round wire spool (I cannot remember the name that they can them), it I has both a top and bottom wheichare round, and there is a sturdy center holding the two together. They are basically rough wood and they line up like a picnic table. They can be rolled out. Like you can roll a spool. Then you have the choice of refinishing t or leaving. You will need help to put it on a truck, and a truck to bring it home.

They are free. The perfect shape for a round granite table. You can cut it down if needed. Hope this works! They throw these out in dumpsters but like to be asked. lbkingboyle@gmail.com

https://www.google.com/search?biw=1016&bih=642&tbm=isch&sa=1&ei=RsdFWoOLHqKcjwSmq5DoCQ&q=build+a+bar+height+table+base+for+granite+countertops&oq=build+a+bar+height+table+base+for+granite+countertops&gs_l=psy-ab.12...26719.28930.0.33624.6.6.0.0.0.0.95.479.6.6.0....0...1c.1.64.psy-ab..0.0.0....0.OwiRdo8lxag

My pleasure.