a metal block below a pot

Why would you want to do this?

• They multiply a stove's power.
  • In some cases (e.g. stir frying), it's desirable to have a more powerful burner. Unfortunately, most indoor stoves are usually relatively weak (because more powerful stoves require you to seriously upgrade your A/C and ventilation systems, and fire safety systems, and most home owners don't feel that's worth it).
  • When cooking without a metal block, the important metric is the stove's power — the amount of energy it can deliver, per unit of time. If you dump too much cold ingredients in the pan at once, the pan's temperature will plummet, and it will stop being able to sear. But when you're allowed to "save up" a bunch of thermal energy in the metal block right before you start cooking, then more important metrics become the max temperature of the burner, and how much thermal energy the metal block can store. (and how long it takes to fully charge the block, and the block's baseline heat dissipation rate, and and ...)
• They turn every pan into a cast iron pan, in terms of ability to remain hot after putting cold ingredients in them.
• They help eliminate hotspots.
• If you're doing multi-hour slow cooking, some stovetops — especially gas stovetops — aren't great at maintaining a steady low temperature. A diffuser will moderate the temperature, allowing all stovetops to do slow cooking and long-term simmering. It serves a similar role as a double-boiler, though it doesn't reduce the heat as much.

Some products you might consider:

• Stryker Welding and Fabrication
  • materials they stock
  • contact
  • Ebay > SWMetals
• heat diffuser plates
  • copper heat diffuser [amazon] [ebay]
    • Duparquet
    • BellaCopper
    • Rachiele
    • TODO: Wouldn't the copper surface get lots of dents and dings, since it is a much softer material than the steel pans that will be moved around on it? Does it make sense to attach some steel sheet metal to the top? (whether by cladding or riveting)
  • aluminum heat diffuser
• I've seen people use a stovetop griddle (that typically straddle two burners) or a baking steel (possibly rectangular in shape so it can cover two burners), and using it as a surface that you can put multiple pots on.
• Safety indicator — A diffuser can store a lot of energy, and can remain hot for a long time, posing a real risk of burns. It would be helpful if there was some kind of "I'm hot!" indicator built-in.
  • I explored everything from thermochromatic thermometers, glass thermometers, but what I eventually settled on is the bimetal thermometers that are flat on the back. [2] [3] [4] [5]

There are two materials-science properties that are at play here:

What size diffuser is good?

• BellaCopper says "we use the 8 and 9 inch most often in our kitchen"

let's build this (Jan 2025)

Buy from this place, it seems like they'll charge a little less if there's enough cut-offs and scrap and such.

• Stryker Welding and Fabrication
  • materials they stock
  • contact
• Buy two 1/8" thick copper plates, a 1/4" aluminum plate, and if possible, two stainless steel sheet in the same shape, for the top and bottom. And maybe a short bit of copper rod, maybe 0.5" diameter, so I can make my own rivets?

Connect all the sheets together using countersunk rivets. Ideally the top and bottom surfaces would be entirely flush, to make cleaning easier.