Toy box manual step 1: how to start metal 3D printing

• 1
  Key takeaways
• 2
  What toy box manual step 1 actually asks you to decide
• 3
  Deciding whether the part belongs in metal AM at all
• 4
  Design rules that keep the first build from distorting
• 5
  Material selection beyond stainless and aluminium
• 6
  Step by step: running toy box manual step 1
• 7
  Which process fits your step 1 goal

Most first attempts at metal additive manufacturing fail before the file is uploaded. The part is designed, quoted, printed, and then it turns out nobody agreed on what "good" means. Toy box manual step 1 exists to stop that. It is a written goal: what the part does, how many you need, which surfaces touch other parts, and which dimensions can move.

Write the goal in five lines. Line one is the function: does the part carry load, guide motion, or only cover something? Line two is quantity, from one prototype to a 10,000-part run. Line three is the critical dimension and its tolerance. Line four is the material family. Line five is the deadline and the inspection you expect.

The order matters. Function decides geometry. Geometry decides whether printing, milling, or casting is the cheaper route. Quantity decides tooling. Only after those four are fixed does a tolerance number mean anything, because tolerance is what the shop spends time and money to hold.

A goal that says "as accurate as possible" gives the shop nothing to work with. A goal that says "bore Ø12 H7, flatness 0.05 mm on the mounting face, ±0.005 mm on the two locating holes" is a different conversation. The second one gets an honest answer about process and price.

Metal AM wins when the geometry is internal, organic, or impossible to reach with a cutter. Conformal cooling channels, lattice structures, and merged assemblies with no joints are the classic cases. If a part has three flat faces and a drilled hole pattern, CNC milling will usually be faster and cheaper.

The break-even is not about complexity alone. It is about how much material you remove versus how much you add. A bracket that starts as a 200 g block and ends as a 30 g part wastes most of the stock. Printing adds only what the part needs, then machining cleans up the interfaces.

Quantity changes the answer again. One printed bracket can beat a full machining setup. Two hundred identical brackets usually favor CNC, die casting, or a printed pattern plus finishing. We run both routes in-house, so the comparison is made on the same drawing, not on a supplier's preference.

There is a third case worth naming: the hybrid part. Print the complex core, then machine the sealing faces, bores and threads to final size. This is where ±0.005 mm and Ra 0.2–0.8 μm become reachable without redesigning the whole component.

• 1
  Choose AM whenInternal channels, lattices, merged geometry, low volume
• 2
  Choose CNC whenPrismatic shapes, tight bores, high quantity, standard stock
• 3
  Choose hybrid whenComplex core plus sealing faces or precision bores

Metal printing builds in layers, and each layer carries heat. Thin walls cool faster than thick ones, so the part pulls itself out of shape. Keep unsupported walls at 1.0 mm or above for most alloys. Going below that is possible on small areas, but expect to inspect every one.

Overhangs need support, and supports must be cut off later. A face that is supported will not look like a machined face. If a surface is cosmetic or seals against a gasket, orient it upward or plan a finishing pass. A 45° rule is a rough guide, not a law; check the actual angle on your model.

Holes print undersize. A Ø5 mm hole often comes out near Ø4.8 mm because of melt pool shrinkage and surface adhesion. Design the hole at nominal and add a reaming or boring step, or model it 0.2 mm undersize when the hole is not critical.

Sharp internal corners concentrate stress and trap unmelted powder. A 0.5 mm radius at the bottom of a pocket costs nothing and helps both the print and the cleaning step. Powder that cannot escape becomes a trapped void, which is a defect you will only find on a CT scan.

Stainless steel and aluminium cover most first projects. Beyond that, the alloy list matters more than the process name. Titanium TC4 (Ti-6Al-4V) suits light, stiff parts in aerospace and medical work. Inconel holds strength at high temperature. 17-4PH gives you a hard, corrosion-resistant part that can be aged after printing.

Copper and brass alloys are the thermal choice. C101 and C110 conduct heat far better than steel, which is why they show up in heat exchangers, motor housings and cold plates. Beryllium copper adds strength and is used for tooling inserts and spring contacts.

Magnesium AZ31B and AZ91D are light, but they need careful handling because fines are reactive. We machine them, and the same housekeeping rules apply to printed magnesium. If you are not set up for that, pick aluminium instead.

Plastic is not off the table. When the part is a cover, a jig, or a fit-check model, ABS, PC, POM or PEEK may do the job at a fraction of the cost. PEEK survives heat and chemicals; PA and carbon fibre grades add stiffness. Step 1 is where you decide whether metal is really required.