Induction heaters have been around for eons. Italians have been using them to braze frames for over sixty years.

They use the same principle as glass cook tops, and are extremely efficient, so a good choice for volume work, but may be too costly for low volume situations.

So, don't run out and buy one before doing research to see if it's suited to YOUR needs.

It's been years since we had one so things might have changed a bit.

BITD you need a water cooling system to keep the coils from overheating at brazing temps.

You need different custom made coils to evenly heat the various joints.

You might also need an inert atmosphere system, depending on your specifics.

Also make sure any plug in unit is powerful enough to heat frame joints to working temps.