Fill in after tracing (Leca)

[Plupp 192863]

Hello,

I'm planning to install some fixtures on an outdoor wall that is basically made of Leca blocks. To avoid having an unsightly electrical cable along the wall, I'm thinking of creating a small channel/groove and then neatly covering it up to hide the cable.

What's the smartest material to use? Simple concrete mixed together?

Starting my career on BH with a simple question

 

[anders07]

Plaster mix works well. If it's a small amount, there is ready-mixed "husfix" available to buy.