Solid Modeling – 3D Modeling With Parts

Solid Modeling – 3D Modeling With Parts

10 min

Solid modeling allows you to make complex parts in Roblox. Starting with very simple parts (blocks, spheres, wedges, and cylinders), it’s possible to create almost any shaped object imaginable!

The main advantage of solid modeling is that objects created become single parts. This can result in a significant part count reduction and improve game performance.


The main function when using solid modeling is called Union. To use it, select the parts you want to combine and click the Union button in the Model tab. This will create a new part called Union (which you are free to rename).


Solid modeling allows for more than just joining two parts together! Parts can also be removed from other parts using the Negate button. To use it, select a part and click the Negate button in the Model tab.

This will convert the part to a “negative part” (it will turn red and translucent to indicate this). Now, whenever this negative part is unioned with a normal part using the Union tool, the section of the parts that overlap will be cut out.


If you don’t like the result of a union, you can undo it by selecting the unioned part and clicking Separate. This will break the union apart so you can resize and rework the construction.

Level of Detail

By default, solid-modeled parts will always be shown in precise fidelity, no matter how far they are from the game camera. This improves their appearance when viewed from any distance, but if a place has a large number of detailed solid-modeled parts, it may reduce overall game articles/Improving Performance|performance.

To dynamically control a solid-modeled part’s level of detail, change its enum/RenderFidelity|RenderFidelity property to Automatic. This will cause the part to be rendered at a different level of detail depending on its distance from the camera:

Distance From Camera Render Fidelity
Less than 250 studs Highest
250-500 studs Medium
500 or more studs Lowest
  • model
  • parts