I use checkering tools,cause I already have and use them alot in other work.
Most of the ckr'g tool makers sell a 'jointer'. A single line tool with a very long cutting edge.
It's used to correct mistakes or near mistakes in checkering where a line spacing is off.
The long cutting edge makes it easy to straighten out the offending area of the line (if you don't go too far).
Use a jointer for cutting a long straight single line.
Then you could use any number of border style checkering tools which are available for different styles of mullered, spaced, doubleline, etc borders. Use the jointer line as the guide for these.
All you need is a straight line to follow to begin with.
.....but I have to admit that stock scratch moulding tool is neat!