How to Merge Objects in Blender

When modeling in Blender, sometimes you might need to join or merge objects together to make the modeling process easier.

Merging objects allows you to combine different parts of a model into one single object. This process can be especially helpful when you want to manipulate complex models.

In this article, we'll look at how you can merge objects in Blender. We'll start by learning how to join objects, and then learn to merge and subtract in Blender 3.5 by applying modifiers.

1. Joining Objects
When getting started with Blender, one of the fundamental tasks you will need to learn is joining two objects together.

When the objects in Blender are joined together, they are actually not geometrically connected but are simply marked as one object. Although you can rotate, scale, or move the joined objects together, they are technically unattached.

For example, you could be modeling a complex miniature model or a mechanical part that must be assembled after printing. To ease your work, you might join the pieces together in their assembled state while in Blender, then have them printed separately in actuality.

However, before we dive into the steps involved in joining objects, here are a few things to understand:

• The parent: There is always one object that will be the parent of all other objects that are being joined. This could be the most prominent object, the body of a character model, for example. To select an object as the parent, it will need to be selected last.
• Other parts: It's key to remember that even if the objects are touching when being joined, they are not connected together. They are simply intersecting with one another. Joined objects will simply behave as one object when it comes to transforming them.

Without further ado, here's how you can join two objects in Blender:

1. Select the first object by left-clicking on it. This would be the non-parent object.
2. Once selected, hold down the Shift button and then left-click on the other object. This last object is the parent object.
3. Now with every object selected, click on the Object menu.
4. Click on the Join button found in the Object menu.

When selecting the objects you'll realize that one object is highlighted yellow (or arguably a lighter orange) and the other is orange. The object that is highlighted in yellow is the active object which indicates the last selected object.

After these steps, the objects will now act as one. You can also press Ctrl + J after you've selected the objects to quickly join them together. Joining different parts of a model is a handy trick to make manipulating them easier. But what if you really want the objects to be attached together?

2. Merging Objects

As mentioned above, joining two objects does not actually fuse them together since they still exist as separate geometries. To actually fuse the objects together, you can use the Boolean modifier.

Modifiers apply mathematical operations on objects to alter their shape and size in various ways. You can use modifiers to do tons of stuff, such as converting a mesh to a wireframe.

Using the Boolean modifier to merge objects will only work with two objects at a time. However, once you merge the two objects they become one in every sense. So you can repeat the process to attach more than two objects together.

With all that said, you will need to select one particular object as the one that the modifier will be applied to. For simplicity's sake, we'll call this the main object.

Here are the steps involved in adding one object to another in Blender:

1. Left-click on the main object. In this example, we're using the cube as the main object.
2. Now with only this object selected, click on Modifier Properties. This is a blue wrench icon on the right-side bar.
3. Click on Add Modifier. You will now see a list of available modifiers.
4. Select a modifier by left-clicking on it. In this particular case, we are looking for the Boolean modifier.
5. Click on the button next to the section labeled Object. You will see a list of objects appear.
6. Select the object you want to attach to this main object.
7. Tinker around with the Operation section in this modifier. There are three options here: Intersect, Union, and Difference. In this case, we select Union.
8. The objects are now ready to be attached together. To do so, click on the drop-down arrow icon and click Apply or simply press Ctrl + A.

The Operation type you select for the Boolean determines how the objects will interact together. Intersect will only merge the parts where the two objects intersect. Union will merge the objects as they are, and Difference will cut out the parts that intersect.

The Boolean modifier only modifies the main object. When you merge two objects with the Union operation, a copy of the second object will add to the main object. The second object will remain unchanged. You can delete it yourself if you have no use for it anymore.

If you want to learn more about physics in Blender, we've put together a full guide for that.

3. Subtracting Objects

There are times when you need to cut out an object from another object. Like when you want to engrave text or a particular shape into another object. To do so, once again, we can use the Boolean modifier but this time with different settings. Here's how:

1. Repeat the first two steps in the previous section. Remember that the object you apply the modifier to is the object that you're cutting into.
2. In the Boolean modifier settings, select the Difference operation.
3. Now select the other object by clicking on the empty box next to Object text. Find your other object listed there. In this case, we want to select the cube.
4. Finish the process by applying the modifier with Ctrl + A.

To see the subtraction results, you might need to move or delete one of the objects.

If you can't select one object without selecting the other, use the outliner in the top right corner of the Blender screen in the default view. Click on the object, then move your cursor into the 3D editor and move or delete the object.

Blend Objects Together

Merging objects in Blender is an easy process, but there are a few important steps that you need to take to ensure that the merged objects look their best.

Now you know how to merge objects in three different ways, enabling you to do a lot more with your models in Blender.