3,2mm black ABS tube, 25cm length. These tubes have a much better look than the LEGO ones which gives trains a much better look. Available in other colors and lengths

2mm round Brass Rod, 20cm length. Ideal to keep 4mm pneumatic hoses in shape when you need to bend them. Non-magnetic copper and zinc alloy Good mechanical stability

This part is used in the instructions for my Virginian Triplex to keep the BMR knuckle coupler at it's place. It is basically an upside down 2x3 tile with 2 studs at one side. Comes in black only

1mm round Brass Rod, 25cm length. Ideal to keep the 3,2mm ABS tubes in shape when you need to bend them. Non-magnetic copper and zinc alloy Good mechanical stability