PlasticABS
Smooth and easy to mould, so it takes bright colours and crisp shapes. With heavy use it wears to a shine where your fingers land.
Many classic and premium doubleshot sets are ABS.
Keycaps, explained
Two sets in the same colours can feel completely different. It comes down to three things: the shape of the caps, the plastic and how the letters are made.
Profile: the shape
The profile is the height and angle of each row. Sculpted profiles tilt each row towards your fingers; uniform ones use the same cap everywhere. Pick one to see a row of caps from the side.
Plastic and legends
PlasticPBT
Harder and more resistant to shine, usually with a fine matte texture. It's trickier to mould, and long caps like the space bar can warp slightly.
LegendsDoubleshot
The legend is a second piece of plastic moulded through the cap, so it can't wear off. Any colour combination is possible.
LegendsDye-sublimation
Dye is pressed into the plastic with heat, so the legend sits inside the cap and doesn't rub off. It works for dark legends on light caps, not light on dark.
LegendsPad printed or laser
Ink printed on the surface, or marks etched by laser. Cheap and quick, but printed legends can fade or rub off over time.
FitMX-style stems
Most custom keycaps fit the cross-shaped "MX-style" stem used by most mechanical switches. Low-profile and some laptop-style switches need their own caps.
Keycap questions
Which keycap profile is best for typing?
It's personal. Low sculpted profiles like Cherry feel familiar to most people coming from a regular keyboard; tall ones like SA feel retro and loud. If you can, try a few keys before buying a whole set.
Is PBT better than ABS?
PBT resists shine better; ABS takes colour and detail more easily. A good ABS doubleshot set can outlast a thin, cheap PBT one.
Will a keycap set fit my keyboard?
Check two things: the switch stem (most custom sets fit MX-style) and the layout. Sets list the keyboard sizes they cover; small boards often need odd-sized keys like a 1.75-unit right shift.