Hold horse in left hand on lead, hold cart or pvc unit in right hand. Lead horse while dragging the unit. If that's too much pressure, have horse loose in pen & you drag the unit around horse, coming closer n farther, turns, zig zag, whatnot. You may want to touch horse with it, tap her sides & butt with it, gently "run" it into her.Okay this is what my hubby made. She is still in the figuring out her blinkers and bridle stage. She was fine trying to make sure it fit, but when it moved a bit she freaked out. How do you get from the freak out stage to where she will accept it? Bear in mind this is the same little mini from my other post that we recently rescued and was very wild and has come a long ways
Once ignoring it, try again in hand.
If fine with that, hold lead with right hand, but keep horse on left side. Use left hand to drag unit behind horse as you lead it. Easy to do with a mini, much harder with a pony or full sized horse. But, you could add pipe to extend length of the right shaft, one you hold, so unit is fully behind more easily.
Then you can bring it up & have horse between the shafts, wiggle it, have it tap horse's sides.
Slowly add in turns with it bumping horse.
You'll probably need the ends to bend up 45 degrees or it may jab into the ground. Once you have curved ends, you could ask horse to back up into it, then to continue backing, pushing it back.
Or, get a helper with all of that.