Grey resin, ranked by £/litre

Why per-litre, and why the weight-to-volume fudge

Resin is sold in 500 ml, 1 kg and 2 kg containers more or less interchangeably, which makes shelf prices almost impossible to compare. Ranking by cost per litre fixes that.

Where a bottle is sold by weight we treat 1 kg as 1 litre. Strictly that is wrong — standard photopolymer is around 1.05 g/cm³, so a kilogram is nearer 0.95 litres — but it is how the trade quotes it and how buyers compare it, and applying a 5% correction nobody else applies would make our numbers look wrong rather than look right. The comparison stays consistent either way.

The types, and which one you want

• Standard. Cheap, sharp detail, brittle. Fine for display models and nothing that gets handled.
• ABS-like / tough. Less brittle, slightly softer detail. The sensible default for anything with thin parts that might get knocked.
• Water-washable. Cleans up in water instead of isopropyl alcohol, which is genuinely more pleasant and much cheaper to run. Usually a little more brittle, and the wash water is still contaminated waste — it does not go down the sink.
• Specialist. Flexible, castable, high-temperature and dental resins cost several times as much and exist for specific jobs.

For most people printing miniatures or display pieces, a tough or ABS-like resin at a sensible price is the right answer, and the difference between brands at the same grade is smaller than the difference between grades.

The running costs nobody mentions

Resin printing has consumables beyond the resin. FEP film in the vat wears and needs replacing periodically. Gloves are not optional. Isopropyl alcohol is an ongoing cost unless you go water-washable. And failed prints waste resin in a way failed filament prints do not, because a failure often means a vat full of cured sheets to fish out.

Budget for those when you compare a resin printer against an FDM one. See resin safety and disposal and when to replace FEP film.

Shelf life and storage

Resin cures with light, so it lives in an opaque bottle away from windows. Kept dark and at room temperature it lasts a year or more. Cold resin is thick and prints badly — if the room is cold, warming the bottle to normal room temperature before printing fixes more failed prints than any setting change.