You must be wondering how to fix or transform things quickly without wreaking any havoc. Well, Blender usually has many tools to help you, however, there are two of them that can fix any hollow or gap you may have in your model. But be careful, even when the Fill and Join tools seem to do the same, each one affects your objects differently. Do you want to know how to use them? Let's begin!

Fill tool in Blender

You can use the Fill tool to fill a hole in your model, connect faces between them, or link two separate pieces. You just need to select the vertices, edges, or faces on the corner of the hole, press F (which is the Fill Tool's command), and that’s it! This tool is very intuitive, isn’t it?

If you only select vertices, for example, one on the first side and another from the second, when you use the Fill Tool, you will see them attached by an edge.

But, if you select two edges (which are usually equal to four vertices), then the Fill Tool will create a face between the points you’ve chosen.

Something cool about the Fill Tool is that you can make Loops without a big effort. Let’s do an example to create a simple cylinder:

Press Shift + A to create a mesh object, select the cylinder, and delete all the faces around the two flat circles on top and bottom. After that, follow the steps below:

1. Select four vertices to create a single face.

2. Then, select an edge from one of the sides.

3.  Press F and observe how without selecting an edge, the loop is created.

Note: You can do this process only if both circles have the exact number of vertices, but they don’t have to be completely aligned with each other.

Another thing you need to consider is that this tool usually fills it with a triangle if you select only two or three vertices.

Join tool in Blender

The Join Tool, also known as the Join Operation, is like the Fill Tool. Both of them will draw a line bounded by two unconnected vertices, but the main difference between them is that the Join tool is more aggressive in terms of how an object or model can be transformed.

Let’s give an example to make that clear. If you select two different vertices and press F to use the Fill tool, Blender will create an edge between them but won’t split the face. But, with the Join operation, you can divide a face to create more by pressing J on your keyboard:

Depending on what you want to build, either tool may help you create complex models on Blender! What do you think? Which one can help you better?