Of course the first step is to find a patter or make your own. Making your own is the best way to get the best fit on the horse. Usually 4 to 6 oz leather is great for this. First, determine the size of halter that your horse requires. Second, measure the length of the nose band that is already on the halter, the lengths range from 8 to 10 inches. After you have the halter and size desired for the nose piece, I use microsoft word to draw my templates. Just insert an oval shape onto the landscaped page and size the oval to the desired length and height, normally 3 to 4 inches for the height is what I use. Print the page out and mask the front and back with scotch tape. Cut the figure out. Note this template is still flexible, so you may need to practice tracing the shape onto regular paper, before tracing to leather. Now that you have your shape, you need to trace a front and back piece out of the leather. Note: the back piece will need to have tabs so that you will be able to secure the nose piece to the halter with conchos. The next step is to stamp or carve or ink the design onto the front piece. After that use tanners bond to secure the back piece to the front piece. Note: the back piece should have the finished surface of the leather towards the horse's skin. After bonding both pieces, stitch the two pieces together. Next finish the edges by burnishing them and punch out the holes for the conchos, and then you have finished your bronc halter.
I'm sorry it's such a lengthy post, but its not worth posting unless its right. Good luck with making your bronc halter! I have plenty of pics of ones I have made, if you would like examples of different designs I can email them to you.
Chris
rockinjleatherwork@gmail.com
Long Live Cowboys!