This talk is about some special type of profinite presentations called ω-presentations. In 2013, J. Almeida and A. Costa showed how these presentations arise naturally for certain profinite groups corresponding to primitive substitutions. In that context, ω-presentations can be concretely computed with a device called return substitution, a combinatorial construction introduced by F. Durand in 1998. I will present some examples and share stories of my ongoing quest to understand how these presentations can be used in practice.