You can make a sundial using any object.
But there are rules about how you set it up. For example, you need the pointer to give a clear shadow, so choose something with a straight edge, like a stick placed in the ground.
Of course, the stick must also be out in the open, where the sunshine can reach it!
On a sunny day, place a stick upright in the ground. Place a stone on the ground where the shadow falls at each hour (use a clock to get the correct time).
Are the stones evenly spaced?