What you need
A scrap bit of railway iron, I would say at least 30 cm long to start with
Optional - tree trunk (and saw to cut shelf), mounting plate from scrap steel, small castor wheels
Grinder - I used a 125cm and 230 cm grinder to cut the horn
Die grinder or files to smooth cuts
oxy torch to cut curves, or find a mate who is happy to do it for you.
grinder flap discs - I used 40,60,80,120
Optional - welder
Get your bit of iron and roughly mark out your design, Then get an oxy torch and cut it to your liking. Personally, I have no idea how to use an oxy so asked someone who does to use their equipment to do it for me. I did initially also try and cut the curves progressively with a grinder which didn't look too bad but I decided to to get them tidied up with the oxy.
At this stage I had tried shaping the horn by using a grinder but it doesn't look that great.
I then decided to tidy up the top and ended up going a mad on the finish using the grinder flap discs - not sure how long it will last!! I started with 40 and went through to 120 grit.
One side of the horn has a sharp edge and the other is rounded
1. Drill a hole in the anvil
2. Drill some mounting holes - in hindsight, bigger holes and using better bolts would have probably looked a lot better than tek screws.....
I then decided to take inspiration from another Instructable I found (https://www.instructables.com/id/Railway-Line-Anvil) and a couple of others I found on the net to finish things off and provide a bit more flexibility.
I mounted the anvil in a tree trunk together with another bit of iron mounted vertically - the vertical iron is welded to a scrap of steel to provide more fixing points to the tree trunk. I then put wheels on the back so that it was portable around the shed when tipped backwards......
I found that the vertically mounted iron is much quieter when being hit.
Hope this is useful to someone.