A new update has been released, you can view the full changes on our blog post.
https://sbox.game/news/update-26-01-07

Sandbox Mode Entities
I wanted to provide a bunch of built in entities in Sandbox Mode. I think in GMod things were automatically made into tools, when they didn't need to be. Like lights for example.
In Sandbox Mode we have a bunch of built in entities, and you can use entities from the workshop too in the same way. Here's an example of lights, fog and NPCs being created.
Sandbox Mode Controls
Entities in Sandbox Mode are controllable now. This is early stages, but right now you can bind them to your in game inputs. The controls only work if you're in a chair connected to them somehow.
What this means is that when you make something, anyone can control it. You can duplicate it and you and a friend can control their own copies.
Changelog
🎁 Added
Physics: Updated Box3D
Physics: Added Rigidbody.EnhancedCcd which is useful for fast-moving objects like bullets or rockets
Mapping: Nudge mesh selection with arrow keys
Mapping: Can save mesh selection as a model
Mapping: Mesh collision uses per triangle physics materials (like Hammer)
Mapping: Attempt to retain selection switching between modes
Networking: NetworkFlags + Transform Sync Flags
TextRenderingScope supports font smooth & 1px aliased outlines
Standard thumbnail texture loader e.g thumb:entities/sents/npc/scientist.sent
Prop inherits Rigidbody properties like mass that were set in ModelDoc
CameraComponent treats CustomSize as an override instead of being used as a fallback
🧼 Improved
UI Panel animations use double precision time
Simplified WheelJoint creation - placed on the wheel, axis and suspension is logical, gizmos display axis and suspension
Mapping: Fast Texturing Tool supports tiling, world mapping, and more
New Pause Menu
Main Menu cleaned up styles
Many BaseControls now SupportsMultiEdit
Renderer: Tiled culling layer ported from C++ to C#
Volume is formatted as a percentage % in the settings menu @DrakeFruit
🪛 Fixed
CrashReporter still reports even if Sentry fails
Mapping: Bevel tool steps match closer to Hammer, added smooth normals
Scope last selected SceneViewportWidget to SceneViewWidget
Video recording: pass the muxer options
UI/Panel Eyedropper tool works with recent changes
Wheel joint steering axis
Fallback to shortcut without modifier if the shortcut doesn't exist with modifier (allows things like tool switching while modifier is down) (#3653)
Sound previews start at playhead position
Editor camera sticking in place at very low speeds
Sprite editor origin
Opaque & non-opaque sprite sorting
Unduck headroom check failing
Don't discard normal in line compute shader when there's 2 points - fixes not being able to rotate points of line when there's only 2 objects
Physics aggregate data causing crashes
Only draw meshes in highest lod for Graphics.DrawModel etc.
Mapping move mode gizmos initial state
Actiongraph editor regressions
ByteStream memory leaks
Editor shortcuts
LargeNetworkFiles requesting non-existant files would crash the server
Crashing connections by sending invalid data or JSON
WorldInput state being stomped
Gizmo selection crash when TypeLibrary lacks a component type
Transition background-image-tint
Editor command line argument parsing
SceneLineObject loading Materials & ComputeShaders on non main thread causing a crash
"Apply to Scene" shortcut
ALT input not working in the editor
CodeGen Preprocessor Defines Fix
Compiler: get rid of "library" assembly prefix when publishing
🚯 Removed
Obsolete vertex attribute array
Obsolete WorldInput class (Use the component)