The Q menu

Spawning props, weapons, tools and vehicles: the Q key.

Open the spawn menu

Hold Q. The game visually pauses: categories on the left, a preview in the middle. Release Q to close it.

On Elipcee some entities are filtered (no map bombs, no cheat NPCs). The rest of Sandbox is there: props, tools, allowed vehicles.

Useful tabs

Props
Crates, boards, furniture, palettes. This is what you build with.
Weapons
Base GMod weapons. Server ARC9 guns also come from the loadout (C menu).
Entities
Special objects (balloons, hatches, sometimes vehicles).
NPCs
Often limited or blocked: real PvE fights are in Elipcee zones.
Vehicles
Cars / Glide if the server allows them.
Tools
Tool Gun tools: weld, rope, no-collide, camera…

Placing a prop

Click a model. It appears in front of you, often already frozen. With the physgun (purple weapon) you move it. Right-click freezes, left-click holds.

Too many props and the server or your personal limit can block you. Undo (Z) removes the last one, and Q menu cleanup wipes your props.