I want to be able to paint in minecraft but I can't figure out a efficient way to draw without gaps in between.

Here is my skript:

Code (Text):

1. on rightclick with shield:
2.     wait 10 ticks
3.     while player is blocking:
4.         test(player)
5.         wait 1 tick
6.    
7. function test(p:player):
8.     set block at target block of {_p} to stone

The problem is, there are gaps in between when drawing so I am trying to find a way to make this skript work without gaps, thank you for your help!