Simple 2-Speed 6WD for teams with few manufacturing resources

[Madison]

I'll start with the bill of materials.

All prices are per item/package

Frame
(1) - C-Base Chassis Kit (AM-0952) - $155.00
(2) - AM Shifter w 2.56:1 Spread (AM-0001) - $350.00
(4) - 16 tooth, 1/2" keyed bore #25 chain sprockets (AM-0277) - $11.00
(1) - 3/8 Screw Size x 2.5" Long Nylon Spacer (94639A621) - $8.62
(1) - 3/8 Screw Size x 1.25" Long Nylon Spacer (94639A863) - $6.80
(1) - 32" x 48" x 1/8" Thk Perforated PVC Sheet (92985T25) - $51.11
(1) - 12" x 24" x 1/4" Thk ABS Sheet (8586K372) - $23.95

Wheels
(6) - 4" x 2" VEX Pro Wheels (IFI-WHEEL-420-38) - $39.95
(6) - 4" x 2" Roughtop Tread (ROUGHTOP-420) - $4.95
(4) - Sprocket Hardware Pack (IFI-SPROCKET-HDWR-X8) - $3.99
(2) - Dual Sprocket Mounting Hardware (IFI-SPROCKET-HDWR-DUAL) - $4.99
(8) - 36 tooth, #25 chain flat sprocket (AM-0099) - $11.00

Tensioner
(1) - 9/16" ID x 1/32" Wall Thkness Nylon Tube (8628K57) - $4.90
(1) - 1/4" Schedule 40 PVC pipe x 48"
(16) - 1/2" Wide Flat Washer
(16) - 1/4" ID Compression Spring