Thank you, SteveL, for the (quicker than expected) answer. As you expected, I have an inventory icon, but no 3D model. To be honest, I have so far not been working with the def-files, so it took some time, to figure it all out, but with the help of the Wiki I was able to get it working. There are still some issues, like actually not wanting the wrench to appear in the Keys section (as it currently does, since I am using the same mechanism as the keys to use the wrench) and another sound on adding it to the Inventory, but I think, I can figure that out on my own. Thank you again!