This section covers Hawaiian prototype rolling stock in both brass and urethane. The brass kits (HHK series) represent typical narrow-gauge cars used on Oahu's plantation railways, while the urethane kits (OHK series) offer similar prototypes in a lighter material. All kits are designed for HOn3 (1:87 scale, 3-foot gauge) and include detailed castings such as underframe, body, and roof. For brass kits, you will need to solder the parts together, then clean with a mild acid flux. Urethane kits can be assembled with cyanoacrylate or epoxy; wash the parts in warm soapy water to remove mold release before gluing. These cars suit layouts set in Hawaii's sugar cane industry, circa 1900-1940, and can be used with other narrow-gauge equipment of the period.

The HHK1 boxcar and HHK3 Greg cane car are typical of the wooden cars that served the Oahu Railway and Land Company (OR&L) and other plantation lines. The HHK4 flatcar is a general-purpose car for hauling cane or general freight. In the OHK series, the OHK1 cane boxcar and OHK2 Fricke cane car represent specific prototypes with distinctive side bracing, while the OHK3 Greg cane car and OHK4 flatcar are urethane equivalents to the brass versions. When building, note that the brass kits require careful filing of the etched parts to achieve a smooth fit. For urethane, you may need to trim flash from the castings. These models are best suited for modellers who enjoy kit construction and want accurate, detailed cars for a Hawaiian-themed layout.

All kits include basic details like brake wheels, ladders, and couplers, but you may wish to add extra details such as air hoses or interior bracing. For brass, use a low-temperature solder to avoid warping thin sections. For urethane, sand the mating surfaces flat before gluing to ensure a strong joint. The finished cars can be painted with any good quality enamel or acrylic; for a weathered look, consider using chalks or weathering powders. These kits are suitable for experienced modellers, as they require some skill in soldering or resin assembly. They are not intended for beginners. The prototypes are narrow-gauge, so ensure your layout has the correct track gauge. The kits are designed to be compatible with standard HOn3 components, such as trucks and couplers, which are not included.