A linear tape type guide.
You can cut as much as you want.
You can choose from 2mm used in small parts and 3mm which is more commonly used.
One Gunprimer: Panel Line Guide 2 - Straight Line / 3mm is supplied.
Caution
The adhesive strength of the guide tape is reduced by oil. If the guide tape does not adhere to the part, remove the oil from the surface before attaching it.