Custom Block Outline
by Fiverok
Custom Block Outline replaces the black block selection outline with a colored one that players pick and resize in a configuration menu opened with the K key.
What it does
On the client, the outline drawn around the block a player looks at can be recolored and thickened. The default black line is swapped for cyan, blue, red, green or black, and the colors can be switched directly in-game without leaving the world. The line thickness is adjusted with plus and minus 0.5 buttons, from ultra-thin to a bold, maximum-visibility line.
The mod is useful when the default outline is hard to see, such as in deep dark caves or when building complex structures with many dark blocks. Changes apply instantly, so no world reload or game restart is needed. Because it is client-side only, the server and other players do not need it, and it can be added to any Forge 1.20.1 installation.
Installation needs only Forge for 1.20.1, with a single build released as 1.0.0 on 2026-06-04. The mod is released under the MIT License, but it is not open source.
Key features
Colored block outline
The black selection outline is replaced by a highlight in a chosen color, making the targeted block easier to read.
In-game color switching
Cyan, blue, red, green and black can be selected directly in-game, with changes applied immediately.
Adjustable thickness
The line width is set with plus and minus 0.5 buttons, from ultra-thin to a bold, maximum-visibility outline.
Configuration menu
Pressing the K key opens the configuration menu where the color and thickness are chosen.
Gallery
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Deep caves and dark areas
A brighter outline keeps the targeted block visible where the default black line blends into the surroundings.
Complex building
Players constructing detailed structures can make the outline stand out against dense blocks of similar tones.
Who it’s for: Players on Forge 1.20.1 who find the default black block outline hard to see. The mod requires no server installation.
How it compares
ModContours is an MIT-licensed, open source Forge mod for 1.20.1, client-side only, so it has the same environment and version as this mod. Neon Selection Box is also client-side only and open source under the GNU Lesser General Public License v3.0 only, but it is built for 1.16.5 rather than 1.20.1. Full Hopper Glow is a Forge mod for 1.20.1 – 1.20.6 that runs on client and server and is not open source.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Custom Block Outline | Forge | 1.20.1 | Client-side only | 2026-06-04 |
| ModContours | Forge | 1.20.1 | Client-side only | 2026-06-30 |
| Neon Selection Box | Forge | 1.16.5 | Client-side only | 2023-06-16 |
| Full Hopper Glow | Forge | 1.20.1 – 1.20.6 | Client and server | 2026-07-16 |
Questions
Does Custom Block Outline need to be installed on the server?
Which Minecraft version does Custom Block Outline support?
Can the outline color be changed without restarting the game?
In the catalog
Custom Block Outline is one of 12,078 Decoration mods on ModsFinder, and one of 6,149 Decoration mods for Forge. 34,764 mods support Minecraft 1.20.1.
Similar mods
What the author says
A simple yet highly useful client-side mod that replaces Minecraft's default, boring black block selection outline with a vibrant, fully customizable colored highlight! Now you can perfectly see which block you are targeting, even in the deepest, darkest caves or while building complex structures.
Official listing
- Modrinth page
- modrinth.com/mod/custom-block-outline
- Owner
- Fiverok
- Published
- 2026-06-04
- Updated on Modrinth
- 2026-06-04
- Facts verified
- 2026-10-15