I got bored one day and decided to make this. I hope it gives you some ideas.
I'd like to see you improve upon it.
Step 1: Step One
Get the horseshoes you want to use. Hopefully all the same size.
You'll also need a welder (I used flux core wire) and some knowledge on how to use it.
Step 2: Step Two
Once you have your shoes, start from the bottom up.
Depending on how many you choose (I used seven) determines how the set up is.
I added the seventh as the "trunk" after the tree was finished.
Step 3: Step Three
Make the base.
I chose three larger shoes for this step.
Step 4: Step Four
Weld the tree and base together.
Step 5: Last One
Paint it or leave it the natural metal color (I suggest clear coating to keep from rusting). Add ornaments and such.
I'll finish mine up after making a star out of horseshoe nails.
That'll be posted at a later day.
Step 6: Bloopers
My hood broke when I was getting started. Luckily I had paracord on hand.