First of all, track elements in TrackMasters are internally referred to as TrackParts. The word TrackPart may appear here and there on this page and means rigorously the same thing as "track element".
TrackMasters comes with a certain number of track elements built-in, and these elements all have an ID ranging from 1 to 255. However, it is possible to add an unlimited amount of new track elements to the game via modding, as long as the name of each new element is unique.

⚠️ Warning

As of now (TrackMasters 1.38), custom track elements can only be cosmetic.
That means that despite being placeable on a track, they cannot be made part of the actual path the player has to follow from start to finish to make a full lap. The navigation system will ignore them entirely.
This limitation is due to the complexity of making track elements navigatable by the game, that makes it hard or impossible to predict how a track is going to behave without the in-engine developing tools.
In the future, this limitation may be removed and a tool may be introduced to make including navigatable track elements in a modpack possible.

This document will rely heavily on the example modpack (LOUVESYSTEMS' STATUE.PAK) to provide examples with each explanation.
You can find it in in the SAMPLESP folder, in the game's root directory. If you do not find it, you can also download it here and unzip it by yourself.

What trackparts are made of

A trackpart can be made of many things, but needs at least the following to work in a satisfying manner:

• A track definition, which is a text file declaring what this trackpart is made of, how is it named, how will it work, etc.
• Usually 1 model
• and 1 material, aswell as 1 texture to go with it.

The definition file

The definition file for any trackpart must be put at the virtual path /TRACKPCS/<My File>.YML. The name of the file is of no importance, but you should probably give the file the same name you intend to give to your trackpart.

Similarly to the meta file of your modpack, it is a YAML text file.
Most properties of the definition file are facultative and may or may not be left to their default value, but at least one information must be explicitely given for any custom track element: the ID.
The ID of your track part is a string, it can be of any length and contain any valid UTF8 character. It should be unique enough so that no other track element ever created in a mod can hold the same name.

When saving or loading a track, that ID will be used to store the trackpart in the track file - if it gets loaded later and the trackpart with that ID cannot be found, it will simply be skipped. However if another trackpart is currently loaded with the same ID, it will be replaced on the track with whatever track element is currently loaded with that ID.

ℹ Note

It is impossible to override/replace base game track elements with custom track elements. The IDs of base track elements are a number, while the IDs of custom track elements can only be strings. They are also stored in a different fashion inside the trackfile.

Properties

Property	Type	Default value	Description
Id	text	N/A	MUST be filled with the ID of your track element, or it will not be loaded. Can be any string.
CanBePlacedRepeatedly	boolean	false	Should a repeated click in the track editor allow the player to lay this track as many times ?
CanBeBuiltUpon	boolean	false	Can another track element be placed ontop of this one ?
IsVeryTall	boolean	false	Should all navigation above this track element be blocked ?
LengthOnGrid	positive integer	1	The size of the track element on the grid, on the X axis
WidthOnGrid	positive integer	1	The size of the track element on the grid, on the Y axis
RequiresGroundRemoval	boolean	false	Should the top of the block below this track element be removed when this track element is laid?
AmbientSound	text	None	A looping sound that will be played constantly around this track element, and spatialized.
Model	List of Models	Empty	The models that make this track element, with their collisions
Lights	List of Lights	Empty	The lights that compose this track element, and what they shed light on

Models

A track element can be made of any number of models. However, collision for this element will be handled per-model, so make sure to only enable collisions on the most important models of your trackpart if you have several!

Property	Type	Default value	Description
Path	text	N/A	The virtual path (relative or absolute) to the model file.
MaterialPath	text	Path with an .MTL extension instead of .OBJ	The virtual path (relative or absolute) to the material file.
TexturePath	text	None	The virtual path (relative or absolute) to the texture file. If you've exported your model and material with blender, you will need to specify this.
Position	Vector	false	Can another track element be placed ontop of this one ?
Rotation	Vector	false	Should all navigation above this track element be blocked ?
Collision	text	None	Can be either of the following: Box (collision is a block around the trackpart that takes all the space available), Simple (collision is a block as small as possible to wrap the model), Complex (collision follows the edges of the mesh precisely) or None (no collision at all).
BiomeSpecific	List of texts	Empty	If this is empty, the model and its collision will be present on all biomes. If this list contains one of more biome names (CITY, DESERT, ICE) they will only appear on these biomes.

Lights

A track element can be made of any number of lights - but too many lights might be grouped together for performance reasons, which may alter the way the model is shaded.
Lights are spheres and not projectors, so they will light up every surface placed in their radius.

Property	Type	Default value	Description
Color	Color	Black	The color of the light.
Intensity	positive number between 0.1 and 20	1	Brightness and power of the light
Size	positive number between 0.1 and 10	5	Radius, in meters, of the light
Position	Vector	false	Can another track element be placed ontop of this one ?
Rotation	Vector	false	Should all navigation above this track element be blocked ?
AffectsCars	bool	false	Will the light also affect vehicles surfaces?
BiomeSpecific	List of texts	Empty	If this is empty, the light will be present on all biomes. If this list contains one of more biome names (CITY, DESERT, ICE) the light will only appear on these biomes.

Vectors

Property	Type	Default value	Description
X	number	0	X is the left-right axis.
Y	number	0	Y is the up-down axis.
Z	number	0	Z is the forward-backward axis.

Colors

Property	Type	Default value	Description
r	positive number (0-255)	0	Red
g	positive number (0-255)	0	Green
b	positive number (0-255)	0	Blue

Aliases

Multiple words can be used to signify true, false, and null/empty in a track sheet. These aliases are always case insensitive, so for example YES and Yes will both be parsed to true indistinguishably.

Word	Equivalent to
no	false
off	false
false	false
disabled	false
0	false
yes	true
on	true
true	true
enabled	true
1	true
null	null
none	null
nil	null
undefined	null
noone	null
nada	null
~	null

Example

Id: 1x1_SmallStatue
CanBePlacedRepeatedly: Yes
CanBeBuiltUpon: No
IsVeryTall: No
RequiresGroundRemoval: No
LengthOnGrid: 1
WidthOnGrid: 1
AmbientSound: ~

Models:
- Path: EXAMPLE_FILES/1x1_Statue.OBJ
  MaterialPath: EXAMPLE_FILES/1x1_Statue.MTL
  Position:
    X: 0
    Y: 0
    Z: 0
  Rotation:
    X: 0
    Y: 0
    Z: 0
  Collision: Simple
  TexturePath: EXAMPLE_FILES/1x1_Statue.PNG
  
Lights:
- Color: 
   r: 255
   g: 120
   b: 255
  Intensity: 1
  Size: 5
  Position:
    X: 0
    Y: 6
    Z: 0
  Rotation:
    X: 0
    Y: 0
    Z: 0
  AffectsCars: No
  BiomeSpecific: 
  - CITY

Model and material files

Supported model formats

The only supported model format is Wavefront .OBJ. All the models you provide must be in that format.
Accordingly, the only supported material format is Wavefront .MTL. If you use Blender, exporting a model to OBJ automatically export its model with it in the MTL format.
Textures can be in any format, but are preferred to be in the .PNG format.

⚠️ Warning

Normally, specifying the texture of the model via the TexturePath property should not be necessary, as the material already contains a link to the texture file via the MTL property map_Kd.
However, it appears that to this day (January 2021) blender-born MTL files are missing that property and there is no way to include it automatically.
TrackMasters fixes this automatically by adding a map_Kd property to the MTL file on loading, given that TexturePath is provided in the model definition. If you MTL is malformed, and it is likely to be if you export it with blender, please make sure to always indicate TexturePath.