How can I replace edges by gaps?

I have a solid door. I want to divide it along the current edges:

Here's a non-destructive proposal using Modifiers:

1. Add an Edge Split modifier set to angle 0
2. Add a Smooth modifier limited to the width axis
3. Add a Solidify modifier
4. Add a Bevel modifier
• .. this makes my answer look so vulgar :D – Robin Betts May 12 at 8:33
• @RobinBetts But still valuable - if someone doesn't need a non-destructive solution, yours is quick and easy. – Gordon Brinkmann May 12 at 8:47

A common strategy for creating adjacent planks, bricks, tiles, etc., is to divide regions before giving them thickness.

While the door is still a plane:

1. V Rip the edges between planks
2. Assign a Solidify modifier
3. Assign a Bevel modifier, by angle

• @Chris :D.. now the Mirror modifier should come more naturally.. (rip, 'L' select linked under hover, delete faces on one side) – Robin Betts May 12 at 8:06
• @RobinBetts Only that for the original design of the post you can't use the Mirror modifier that easy ;) – Gordon Brinkmann May 12 at 10:35

The answers of @DredWolf and @RobinBetts are both good solutions if you're creating from a plane, these answers are how you should do it. Nevertheless, here's something additional to that solution. If you already have an extruded object like the one in your screenshot and you maybe want small grooves between those parts to separate them, you can do the following:

1. Select the edges where you want to create grooves.
2. Use Ctrl+B to bevel those edges so that each edge becomes a doubled edge.
3. Keep the selection of the new face loops, hit Alt+E > Extrude Faces Along Normals.
4. Scale them inwards to your liking (or outwards for ridges).

If you want to make real gaps so that there is space between them, you can use this method. It uses LoopTools (Preferences > Add-ons > Mesh: LoopTools).

1. Select edges as before.
2. Bevel as before.
3. Right-click on the object for the context menu. Choose LoopTools > Bridge. In this case it only deletes the faces, of course you can do it without LoopTools. Just hit X > Delete > Faces. The advantage of LoopTools is, it keeps the edges selected.
4. With the edges still selected after Bridge (or select them after deleting faces), now hit F to fill the open sides.
5. You've separated the door with gaps between the parts.

• That's a really cunning use of the 'Remove Internal Faces' feature of LT > Bridge which I've previously never bothered with. Now I'm going to have to resist my muscle-memory to work it in :) – Robin Betts May 12 at 8:27