Resin castings, and increasingly 3D prints, replace the simplified parts of a kit with something far closer to the real thing. Typical examples include brake sets with drilled discs, engine components, steering wheel hubs, quick-release bonnet pins and material for seat harnesses. Most items are aimed at 1:24 and 1:20. These are the unobtrusive components that turn a good build into an excellent one, and below we suggest where to start with them.
They are individual upgrade components, each aimed at one specific weakness in a kit. Injected plastic cannot do undercut shapes or very fine ribbing; a resin casting or a 3D-printed part can. The section holds brake discs with calipers, engine and intake parts, bonnet pins and door locks, steering wheel hubs and rims, and woven material for making harnesses at a realistic width.
The upgrades that pay off are the ones you can still see when the model is finished: brakes behind the spokes, the interior, and everything under an opening bonnet. On 1:20 formula car model kits the exposed mechanicals are the whole point of the subject, so detailed brakes and engine parts practically ask to be used.
Match the component to the scale of the kit, most often 1:24 and 1:25 car model kits. Some parts are designed for a particular kit named in the title, while generic small items such as door-lock plates will serve you again and again.
Resin sands easily and takes cyanoacrylate well. 3D-printed parts have exceptionally crisp edges, and the small support marks from printing need nothing more than nipping off and a light sanding. Degrease both materials before painting, because release agent and print residue stop primer keying, and work with resin dust under extraction or at least with a mask on.
Decide which parts you are replacing before the first sprue is cut. A brake set usually means opening out the back of the wheel or thinning a hub, and a resin seat often needs the kit floor adjusting. Doing that while the chassis is still bare plastic takes minutes; doing it after the interior is painted costs an evening. Test-fit each casting in place, mark what has to go, and only then start removing material.
Every upgrade category is listed together in accessories for car and formula models.
