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 - Aluminum Standoff for Raspberry Pi: 11mm Length, 4mm M2.5 Thread, M-F (4-Pack)

Pololu 1951 - Aluminum Standoff 1.25 4-40 M-F 4-Pack - Kamami on-line store

Stand Off

Pololu 1975 - Nylon Spacer: 12mm Length, 4mm OD, 2.7mm ID (25-Pack) - Kamami on-line store

Pololu - Aluminum Standoff 1.25 x 0.25 4-40 M-F 4-Pack

Pololu - Aluminum Standoff 1.25 x 0.25 4-40 M-F 4-Pack

Aluminum Standoff: 1/4 Length, 4-40 Thread, M-F (4-Pack), POLOLU-1946

Aluminum Standoff: 1/2 Length, 4-40 Thread, F-F (4-Pack), POLOLU-2091

Pololu - Romi Chassis Expansion Plate - Black

1516 Series 8mm REX Standoff (M4 x 0.7mm Threads, 96mm Length) - 4 Pack, goBilda GB-1516-4008-0960