Don Morrison has been hand crafting omnidirectional loudspeakers for about 50 years in Toronto ON. They were originally based on the design of the Hegeman omnidirectional speaker (Morrison was mentored by Hegeman).
The ones my buddy has in his main system are a transmission line woofer (metal) and soft dome tweeter per speaker and separate transmission line sub woofer (two boxes per channel).
They image like NO other speaker I know of… and the Fosi V3s are replacing 70 watt class A monoblocks. They are modified with Sparko op amps and are settling in nicely.