This is what my garage looked like before I started to nail some 75 x 18 laths across the wall
After a couple of hours this is what I achieved
Method was simple
Nailed uprights vertical down the wall about 800mm apart 75 x 18
Then starting from a level position as far could reach up, I screwed on 75 x 18 mm laths at exactly 18 mm apart
using off cuts of the 75 x 18 as spacers.
Then to make the pegs for jamming between the rails to hold my tools I cut the off cuts various lengths to suit what I needed to hold. I split the 75 mm side in half making the peg size 37 x 18 mostly 150 mm long.
Not very good at explaining but thought it was a very good tidy up to share.