3D printing filament buyer's guide

Start with 1.75 mm PLA from a brand with consistent tolerance figures. It prints at low temperatures, barely warps, needs no enclosure and is among the cheapest filaments per kilogram, so early failed prints cost very little.

The cheapest in stock on Amazon UK and Eryone UK right now: PLA from £7.12/kg, PETG from £6.65/kg, ABS from £9.99/kg, ASA from £13.80/kg, TPU from £12.99/kg, Nylon from £17.84/kg. A typical PLA reel costs about £13.99/kg. Everyday PLA and PETG are the cheapest per kilogram; flexible and engineering filaments cost more. Prices change through the day, so each material page has today's cheapest.

PLA+ is PLA with additives that make it a little tougher and less brittle, often printed slightly hotter. There's no standard for the “plus”, so it varies between brands. It's a better PLA, not a substitute for PETG.

1.75 mm, unless your printer's manual says otherwise. Nearly every current consumer printer uses 1.75 mm; 2.85 mm (often sold as 3 mm) is mostly for older and some professional machines, and the two aren't interchangeable.

A 1 kg reel of 1.75 mm filament is roughly 300 to 400 metres, depending on the material. That's dozens of small models or a handful of large ones; a slicer tells you the grams each print uses, and the print cost calculator turns that into pounds.

Sometimes. What you pay extra for is diameter tolerance, colour consistency between batches and vacuum-sealed packaging. For decorative prints a budget reel is usually fine; for multi-reel or functional prints, tighter tolerance saves more in failed prints than it costs.

Not for PLA if you store reels sealed with desiccant. TPU and Nylon soak up moisture quickly, so a dryer quickly earns its place; PETG absorbs it more slowly but still prints better dried. The drying chart has the temperature and time for each.

No. PETG prints on an open-frame printer; an enclosure or a draught-free room only helps with large parts. ABS, ASA and nylon are the ones that need an enclosure.

Treat prints as not food-safe. Layer lines trap bacteria and are hard to clean, and brass nozzles can contain small amounts of lead. For brief, dry contact such as a cookie cutter, use a food-contact grade filament and a stainless nozzle, or seal the part with a food-safe coating.

Sealed with desiccant, filament keeps for years. Once opened, PLA stays printable for months if it's stored dry, while moisture-sensitive materials can need drying after a few days in open air. If a reel has turned brittle or starts popping, dry it before you give up on it.

Look at the price history rather than the percentage badge. A real deal is below the typical price the listing has held over recent weeks, not just below a reference price the seller set high. SpoolDeal's deal badges are measured against each listing's own 90-day history for exactly this reason.