How do I attach a model to another model like this?

Question

I have a plugin that has an option to "attach model" when importing one model that is related to another.

In this case I have two models: hands, and weapon. I first import the hands, select the skeleton of the hands, and then import the weapon via the plugin. The weapon then gets attached to the hands in the object list, and the weapon is repositioned correctly so that the "tag_weapon" bone of the hands is aligned with the "j_gun" bone of the weapon:

This is great, but how can I do this manually? I have models of other file types that I want to do the same thing with. When I import them, naturally they won't be attached to the hands in the object list and the bones won't line up.

Answer 1

There are multiple ways to achieve a result like this.

1. Parent the skeleton of the weapon to the desired bone of the other skeleton.

2. Add an object constraint to the skeleton of the weapon to do the same thing.

3. Add a bone constraint to the specific bone of the weapon skeleton to attach it to the desired bone of the other skeleton.

1 and 2 are object-level attachment. 3 is a bone-level attachment. I can't rule out the possibility that this is an object level attachment, that's why I include 1 and 2 in my list. If you share the file, I can further inspect this, or you can check against my screenshots.

Please don't rule out the possibility that the plugin is doing some work before or after the parenting. For example, it could be rotating the objects after parenting, or tweaking the constraint settings. Additionally, for 2 and 3, it is possible to use a different set of constraints to achieve something similar to parenting.

Answer 2

Mr A's answer solves the main question I asked, but for this specific case it wasn't enough. For it to all work properly including animations, I had to do 3 things in total:

1. Join the skeletons of the hands and weapon by selecting the weapon first, then hands, then right-click > join

2. Select weapon model, go to modifiers. It had a pre-existing armature modifier, but after joining skeletons it didn't know what to point to, so I chose the hands model in the "Object" field.

3. Add a bone constraint to the "j_gun" bone (weapon's main bone), and for the parent, set the hands' "tag_weapon" bone (hands' bone designated for the weapon)

Hope that helps anyone with a similar setup