Pololu - Aluminum Standoff: 1/2 Length, 4-40 Thread, M-F (4-Pack)

These hexagonal male-female aluminum standoffs keep parts spaced 0.5" (13 mm) apart and are great for building a multi-level robot chassis. Both ends of these 3/16"-wide standoffs have 4-40 threads. The standoffs are sold in packs of 4.
These hexagonal male-female aluminum standoffs keep parts spaced 0.5 (13 mm) apart and are great for building a multi-level robot chassis. Both ends of these 3/16-wide standoffs have 4-40 threads. The standoffs are sold in packs of 4.

Pololu 2092 - Aluminum Standoff: 7/16 Length, 4-40 Thread, F-F (4-Pack) - Kamami on-line store

Machine Hex Nut: #2-56 (25-pack) - Robot Gear Australia

Pololu Mechanics Accessories - zeroDNA

Pololu 1971 - Nylon Spacer: 4mm Length, 4mm OD, 2.7mm ID (50-Pack) - Kamami on-line store

Aluminum Standoff: 3/8 Length, 2-56 Thread, F-F (4-Pack), POLOLU-2084

Aluminium Stand-off / Spacer Range - Proto-PIC

Aluminum Standoff: 1/2 Length, 2-56 Thread, M-F (4-Pack), POLOLU-1942

Aluminum Standoff: 1-1/2 Length, 2-56 Thread, M-F (4-Pack)

Hardware :: Standoffs :: Standoffs - Aluminum M/F :: 1949P Aluminum Standoff: 3/4 Length, 4-40 Thread, M-F (4-Pack)

Pololu 1977 - Nylon Spacer: 20mm Length, 4mm OD, 2.7mm ID (10-Pack) - Kamami on-line store

Pololu - A-Star 32U4 Robot Controller LV with Raspberry Pi Bridge

Pololu - Romi Chassis Expansion Plate - Black