Finding Stepping ring

I have a Canon 40D with a large 72mm filter diameter lens and I also bought an Olivon T90ED that come with an Olivon SRL camera adaptor. I connect the camera body with the Olivon using T2 adaptor and Olivon SRL camera holder. I discover that this arrangement cannot zoom or un-zoom thus it’s difficult to frame the picture without moving the camera. Thus I would like to use a step down ring from my camera lens to T2 male thread of the Olivon Camera Adaptor.

I am looking for a step down ring from my 72mm lens to T2 male thread of the Olivon adaptor but cannot find anything in the Internet! Could you let me know where could I by such stepping ring. I might need 2 stepping rings to achieve this.