Basically Particle Models

the mod creates a folder on your server, you can upload models into the folder you can list the models in-game with /particlemodels list

To actually display the models you use /particlemodels display <model file with file extension> <particle type> <model scale> <force/normal> <edge density> <players> the command basically works like the vanilla /particle command

the model will be displayed at the position the command is ran at, with 2 axis rotation support,
you can use /execute positioned and /execute rotated/facing to easily position and rotate the model, if the edge density is set to 0 only the model vertices will be displayed

example: /execute positioned 0 64 0 facing entity @p[distance=..15] run particlemodels display cube.obj minecraft:bubble 1 force 1 @a

this command will display a cube model at 0 64 0 that will face the closest player in a 15 block radius, the model will be made of bubble particles (good for moving models since the bubble particle has a very short lifetime), the particles are forced meaning even people with particles turned off will see them

Warning: the mod can lag your server and/or client

thats why theres a limit to how many vertices a model can have, by defauly set to 512 but can be configured, as well as the folder that the mod checks for models

the mod currently can only display vertices and edges as displaying full faces with particles would be too much, even small models would lag, so im not planning on adding face support
if you want to display models with faces, and even texture support check out [cymera's Text Display Models]

supported model types:

• .obj
• .stl (ASCII)
• .ply (ASCII)

Blender can be weird

if your model is consisted of only edges and vertices without any faces blender might just export a blank file sometimes, you can just select everything and press F to create some faces, that usually helps, but keep in mind that .stl automatically triangulates faces meaning those faces will each add 1 edge, so if you do that id recommend using OBJ or PLY models, when exporting you can uncheck pretty much everything, but you need to check "ASCII" when exporting .stl or .ply, otherwise the mod cant read the files

if you dont use blender you can use any CAD software to create models, they all can export .stl files