Has somebody joined parts with ultrasonic welder?
Just glue them 
The material should work if it is a thermoplastic, not a thermoset.
Also, if I remember correctly, the process is better for higher volume because of the cost to setup for specific parts, material type and geometry.
@Mindless thx
@Temujin_Kuechle thx
Finally I’ve used heat welding.
may I ask what the benefit is? Glueing seems so much simpler and faster…