Support Structures Explained: When to Use Them and How to Minimise Cost
Supports add material, print time, and post-processing labour to every print they touch. Understanding when they are genuinely necessary — and when design changes avoid them entirely — directly reduces your cost per print.
Support structures are often treated as an unavoidable feature of FDM printing. In reality, they are a cost that compounds — extra material, extra print time, extra post-processing, and a higher chance of surface defects where the support was removed. Here is how to think about them strategically.
Why overhangs need support
FDM printers deposit layers onto the layer below. If a layer extends horizontally beyond its support — an overhang — the filament has nothing to bond to and sags or collapses. The threshold for unsupported overhangs is typically 45–55 degrees from vertical. Beyond that angle, most printers need either support structures or a design modification.
The cost of supports
Every gram of support material costs money — typically at the same rate as your part material. On a 100 g print with 20 % support volume, you are printing 20 g of support that goes straight in the bin. At £0.02/g that is £0.40 in wasted material per print.
Print time extends proportionally. If supports add 20 % to the model volume, they add roughly 15–20 % to print time — sometimes more, because support interfaces print slowly for surface quality reasons.
Post-processing support removal takes 5–20 minutes depending on geometry and support type. Supports inside enclosed cavities are particularly time-consuming. That labour at £12–15/hour adds £1.00–5.00 per print.
Total support cost for the example above: £0.40 material + ~£0.15 electricity + £2.50 labour = roughly £3.05 added cost per print — entirely avoidable with good design decisions.
Design strategies that eliminate supports
Reorient the model. FDM printers build bottom-up, so rotating a model 180° can turn a problematic overhang into a supported surface. A bridging span in the slicer (horizontal unsupported gaps between two supported points) prints cleanly up to about 80 mm with well-tuned settings — no support needed.
Chamfer instead of flat overhangs. A flat horizontal surface (like the ceiling of a box) requires support everywhere. Replace it with a 45-degree chamfer and the printer can handle it unsupported.
Split the model. A complex single-piece print with unavoidable overhangs can sometimes be split into two simpler pieces that print flat, then bonded with adhesive or mechanical fasteners. This adds assembly time but eliminates support material entirely.
When supports are necessary
Some geometries have no design workaround: human faces and organic shapes, threaded features that must be printed in position, complex interlocking mechanisms. In these cases, choose your support settings carefully.
Tree supports (available in PrusaSlicer, Orca Slicer, Bambu Studio) use significantly less material than grid supports while providing equivalent strength. They are also much easier to remove from organic surfaces. Enable tree supports whenever your slicer offers them.
Interface layers: set support interface layer distance to 0.2–0.3 mm instead of 0 for easier removal. The part surface will be slightly rougher where it touches support, but removal becomes non-destructive rather than requiring tools.
Measuring support efficiency
When quoting or costing prints, check your slicer's support volume estimate before confirming the price. A print where supports add more than 25 % to the total volume is worth a redesign conversation with the client — or a frank note in your pricing that post-processing is included.