How to choose Thread, Needle, Chisel in Leathercraft

You can have other options depending on your taste and experience in handmade leather, because this is an area that requires a lot of creativity and personalization, so nothing is great. For, all suggestions below are based on my experience.

The two main types of thread used in handmade leather crafting:
Line and Polyester

1. Line thread: Made from natural materials. Stretch resistant. Can rot if cared for. More prone to snapping.
2. Polyester thread: Incredibly strong. Rot resistant. UV resistant. Can be easier to thread. Not environmentally friendly.

Line thread on fine leather goods.
Polyester on those out in the elements.

Threads are made up from multiple strands of thinner thread the way these are put together will give a different look and feel to the final thread.
Twisted threads and Braided threads.
Should use Twisted threads will make the thread look more natural.

Thread thickness
0.55mm thread : on thicker leathers
0.45mm thread : on softer leathers

Thread thickness and Stitch mark size
3mm diamond chisels : 0.45 – 0.55 mm thread
4mm pricking iron : 0.55 – 0.65 mm thread
5mm diamond chisels : 0.65 mm thread

Needle Size
size 002 : 55mm x 1.05mm (thicker threads over 0.55mm)
size 004 : 48mm x 0.86mm (threads up until 0.55mm)