I thought about splitting washers and offsetting them and Welding them to a shaft, I just never have. I know you can buy them, but where's the fun in that!
I've done that. They work ok. I only use 1/2" washers so they made a hole about 1 1/2" wide. Don't let them dig too deep until you pull back on them or they just screw into the ground and you have to back them out.