Wax carving tools question

[Vos]

Hi great Carvers of Cookson

I've been asked to make a pendant based on a tattoo. I came up with the drawing below, which I figure is going to be much easier to cast than to hone from solid silver (Rapousse is waaay beyond my abilities).

I'm fairly comfortable I could carve this from wax, but my question is about tools. Do wax carvers such as these HERE have to be used hot with an alcohol lamp, or can they be used cold to scrape away wax? I'm probably going to use green wax as I believe it's harder. The reason I wish to avoid heat is to take my time and not 'overshoot' on depth.

Oh, the hollow tube idea was just brainstorming. The piece will be solid, with the rope and star added later for ease of carving/casting.

Many thanks

Vos