A well-prepared CAD file is one of the biggest factors in 3D printing success. Whether you're sending your first job to a 3D printing service in South Africa or you're refining your workflow, this guide covers the essentials: wall thickness, supports, orientation, and file formats so your part prints right the first time.
Start with a Watertight, Manifold Model
Your 3D model should be watertight (closed surface with no gaps) and manifold (no duplicate or inverted faces, no self-intersections). Gaps or errors can cause the slicer to misinterpret the geometry and produce failed or incorrect prints. Use your CAD software's "check" or "repair" tools, or export to STL and run the file through a mesh repair tool (e.g. Netfabb, Meshmixer, or online repair services) before uploading.
Wall Thickness and Minimum Feature Size
Walls that are too thin will break during printing or use. As a rule of thumb, minimum wall thickness is often around 1–2 mm for FDM and SLA, depending on material and orientation; SLS can sometimes go slightly thinner. Fine details (text, pins, slots) should be at least 0.8–1 mm thick and deep enough to show up after printing. If your part has very thin sections, consider thickening them or discussing with your supplier—they can advise on limits for their process and material.
Orientation and Supports
Orientation affects strength, surface finish, and the need for supports. In FDM and SLA, layers bond more strongly along the build direction than across it; orient critical load-bearing areas so stress is not perpendicular to layers. Overhangs and bridges often need support structures, which are removed after printing and can leave marks or require finishing. Minimise overhangs where possible, or orient the part so that supports are on non-critical surfaces. SLS does not need supports (the powder supports the part), so orientation is mainly about strength and surface quality.
Holes and Threads
Small holes can close up or shrink; design them slightly undersized and ream or drill after printing if precision is critical. For threads, printed threads work for coarse pitches and low load; for better accuracy and strength, use inserts or tap after printing. Specify thread type and size in your order notes so the supplier can allow for post-processing if needed.
File Formats and Export Settings
Common formats accepted by South African 3D printing services include STL, STEP, and OBJ. STL is mesh-based; export at a resolution that captures your geometry without huge file size (often 0.01–0.05 mm tolerance or equivalent). STEP preserves precise geometry and is preferred when the supplier will adjust or machine the model. Always use the unit (mm or inches) your supplier expects—usually mm in South Africa—and ensure scale is correct (1:1).
Clear Communication with Your Supplier
Include a brief note with your file: part name or number, quantity, material or technology preference, and any critical dimensions or tolerances. If a feature is cosmetic vs functional, say so. Local services like 3D Printing Village often offer free quote and design-for-manufacture feedback, so when in doubt, upload the file and ask. A few minutes of preparation and clear communication reduce reprints and delays and get you to a finished part faster. For material choices that affect design (e.g. flexibility, strength), see our material selection guide; for cost factors see cost of 3D printing: what really affects price.
