Here’s a indicator that draws you a horisontal grid at even price levels.
Need to be changed depending on the instrument.

//Actual Line
DRAWHLINE(100)
DRAWHLINE(100+100)
DRAWHLINE(100+(100*2))
DRAWHLINE(100+(100*(2+1)))
DRAWHLINE(100+(100*(2+x)))coloured(0,200,0)STYLE(line,3)

//Optional Extra deviation lines. 
DRAWHLINE(105)
DRAWHLINE(105+100)
DRAWHLINE(105+(100*2))
DRAWHLINE(105+(100*(2+1)))
DRAWHLINE(105+(100*(2+x)))coloured(0,200,0)STYLE(DOTTEDline,1)
DRAWHLINE(195)
DRAWHLINE(195+100)
DRAWHLINE(195+(100*2))
DRAWHLINE(195+(100*(2+1)))
DRAWHLINE(195+(100*(2+x)))coloured(0,200,0)STYLE(DOTTEDline,1)

y=x
x=y+1

RETURN

Can also be written like this for easier change of value

//Actual Line
Linevalue=100
DRAWHLINE(Linevalue)
DRAWHLINE(Linevalue+Linevalue)
DRAWHLINE(Linevalue+(Linevalue*2))
DRAWHLINE(Linevalue+(Linevalue*(2+1)))
DRAWHLINE(Linevalue+(Linevalue*(2+x)))coloured(0,200,0)STYLE(line,3)

//Optional Extra deviation lines. 
DRAWHLINE(105)
DRAWHLINE(105+100)
DRAWHLINE(105+(100*2))
DRAWHLINE(105+(100*(2+1)))
DRAWHLINE(105+(100*(2+x)))coloured(0,200,0)STYLE(DOTTEDline,1)
DRAWHLINE(195)
DRAWHLINE(195+100)
DRAWHLINE(195+(100*2))
DRAWHLINE(195+(100*(2+1)))
DRAWHLINE(195+(100*(2+x)))coloured(0,200,0)STYLE(DOTTEDline,1)

y=x
x=y+1

RETURN