Hey Victor! Of course, you can use whichever material you want. What you may want to do though, is to add a rudimentary armature for the feet as well, like a simple “hand” made of wire. Just so your claws won’t break off and have a bit of support.
With an underlying armature you can also continue to use Monster Clay (or whichever clay you’re using). The armature lends the support CX5 doesn’t need because it can support itself.
If you’re interested, you may want to check out Chavant’s “Castilene” medium or hard if that’s available in Brazil (http://www.castilene.com). It is similar to CX5, though a tad softer. But it still doesn’t need an underlying armature.
Let me know if you have more questions! 🙂
~Lisa