I have constructed a 40KHz, 100W ultrasonic cleaning bath using a thick cooking pot and some off the shelf parts.
Two 40KHz transducers, part number SMBLTD45F40H, were attached to the bottom of a thick wall cooking pot using dual component Epoxy (Home Depot). It is important to mix the correct proportions so it will cure to a solid piece and not flexible as it would dampen the vibration. The ultrasonic generator used was also found at the same place (STEMINC) and it is part number SMUG100W40ND. This generator is 100W and each transducer is 70W when installed alone or 50W each when installed in parallel. You must connect two SMBLTD45F40H and the system cannot be turned ON until all connections are made and the generator is connected to the transducers ATTACHED TO THE TANK. If not, the generator will be damaged. It cost me not to pay attention to this detail!.
Connections are simple. The electrode between the two piezo rings on the transducer is the positive. So connect the positive electrodes from the transducers (in parallel) and connect to the positive output of the generator. Then connect the negative electrodes from the transducers (in parallel) and connect to the negative output of the generator.
In my build I used Glue, instead of having bolts on the bottom of the pan, You con also have bolts welded to the bottom of the reservoir. Depending on the thickness of the wall of the container you will need to check if it is feasible.