Most of the people we talk to are new to how parts get made, so we start with feasibility. The first thing we look at when someone brings us a product idea is whether it can be designed, made, and produced. Those three questions are the fundamentals of product design that sit underneath styling, features, and branding, and answering them early decides how much of the rest of the project you end up redoing.
Which Fundamentals of Product Design Matter Before You Start Modeling?
Three questions come first: can the product be designed, can it be made, and can it be produced at the quantity you need. Each has a different failure point, which is why they are worth separating before any drawing is polished.
We would start the design with a written brief that names what the product has to do, who will use it, and what it can cost. Cost belongs in the brief because it narrows which processes stay open to you later. Add the quantity you expect to the brief as a range, even a rough one, so the process choice is made against a number rather than a guess. Writing it down keeps the work from drifting, and the stages after it are laid out step by step in our full product design process guide. The model comes next, usually built in computer-aided design (CAD) software, and everything else is made from it. The other two questions, whether it can be made and whether it can be produced, both depend on the process you choose.
The model is also where a project starts, so the file matters. Poor quality digital files are a common problem people bring to us, and the file is the first thing the rest of the project depends on. Separately, a mesh meant for printing has to be watertight, so holes and overlapping surfaces get repaired before anything is made from it. If the part already exists and no file does, a scan captures it as a cloud of points that gets meshed into a surface, usually built from triangles. That mesh suits printing and visualization but is not editable engineering CAD, so changing the geometry means rebuilding the model in CAD first.
How Does the Making Method Change the Design?
Every process limits the geometry, so choose the likely method while the design can still change. Injection molded parts need draft angles so the part can release from the mold, and wall thickness that stays consistent so the plastic cools evenly. The mold is built around the part, which means those decisions are settled before the tool is cut. The detailed rules for routed, printed, and molded parts are in our guide to design for manufacturing.
3D printing and CNC (computer numerical control) cutting both skip the mold. Printing needs no special tooling at all, so there is little setup between a model and a physical part. Cutting a part with computer-controlled tools takes programming and fixturing before the first cut, and for a one-off that setup lands on a single piece, so printing usually costs less at that quantity. We route plastics, wood, and soft metals when a part is better cut than printed.
Casting sits between printing and molding. A silicone mold copies the surface flaws on the master it is poured around, so the master has to be finished first, and silicone can release deep undercuts that would call for extra mechanisms in an injection mold.
We would settle the likely method at the concept stage, even before the quantity is fixed. A part drawn for molding carries draft and wall rules tuned to the mold, and printing and routing have limits of their own, so a late switch means redrawing geometry that was built for the other process.
Why Does the First Prototype Change the Design?
A physical part shows problems a screen hides, and in our experience the changes show up mostly on engineering items. On the Barcade controller, the gun handle was adjusted after the first prototype. Changes like that get more expensive and slower the later they land, so the first prototype comes before any tooling.
Treat the first prototype as a test with one job: to find out whether the part works in the method you picked. Bring it to a review with the brief beside it and check each requirement against the physical part, so gaps are written down before any tooling is ordered. What a first prototype should prove, and what it should leave for later rounds, is covered in our guide to common product design mistakes.
Can It Be Produced at the Volume You Need?
It can, as long as the process was picked for that quantity, because the cheapest way to make one part is rarely the cheapest way to make many. A mold is a fixed cost spread across every part it makes, so molding pays off only when the run is large enough to carry it. A silicone mold wears out after a limited number of casts, which keeps cast parts to smaller runs. Neither printing nor routing needs a mold, but printing carries the least setup, which is what keeps one-offs and small batches affordable.
As a rough map, one piece or a handful points to printing, or to routing when the part is better cut, a small batch points to casting or printing, and a production run points to a mold. Real jobs blur those lines, so treat it as a starting point rather than a rule.
Selective laser sintering (SLS) printing fills the gap between a small batch and an injection mold: it is a cost-effective way to cover low volumes until the quantity justifies tooling. Know your quantity range before the design is locked, even if it is a range rather than a single number, because it decides which of these routes the part can take. Settle design, making, and production early and the fundamentals of product design are covered; what remains is refinement.
Because we scan, model, print, route, and cast under one roof, we can work through all three questions with you together. If you want a second opinion on how your part should be made, send us a note on the contact page, or call our Brooklyn team at 718-557-9578. If you are still getting oriented, our beginner’s guide to product design basics covers the wider picture.
Sources: the cost of late engineering changes comes from Kohler, Conrad, Wanke and Weber’s 2008 DESIGN conference paper; the draft and wall-thickness guidance from DuPont’s general design principles for molding; the silicone undercut point from Smooth-On’s tutorial on cutting a one-piece silicone block mold and Xometry’s guide to injection molding side actions; the setup and tooling comparison between printing and cutting from Protolabs Network’s 3D printing cost guide and HLH Rapid’s comparison of printing and CNC work; the mesh repair and point cloud points from Protolabs Network on STL file errors, Formlabs on repairing STL files, Autodesk on point clouds, and Einstar on what a point cloud is; the surface-copying and mold-life points from Formlabs on casting silicone parts and Formlabs’ guide to vacuum casting; and the point about SLS as a bridge to molding from Formlabs’ comparison of FDM, SLA, and SLS.
