Elegoo Mars 4

The Elegoo Mars 4 is a compact 2023 resin printer built around a 7-inch mono LCD. It's the entry model of the Mars line, aimed at home and hobby use: tabletop miniatures, figures and small parts. Its headline number is the 18 μm pixel, half the size of the Mars 3 Pro's.

Build volume is 153×78×175 mm with an 8520×4320 screen and 20 μm Z accuracy. A COB source of 36 LEDs at 405 nm handles exposure, cooled by three copper heat pipes and a fan. Print speed runs 30–70 mm/h at 0.01–0.2 mm layers. Control is a 3.5-inch resistive touchscreen, and files arrive only on a USB stick. The "9K" badge is marketing — that resolution is normally called 8K.

Pros

• 18 μm pixel against 35 μm on the Mars 3 Pro — owners stress that pixel size, not the "K" badge, drives detail (r/ElegooMars)
• At a 50 μm layer, layer lines are barely visible to the naked eye — the verdict of a first-time resin owner (r/ElegooMars)
• Some owners pick the base Mars 4 over the Mars 4 Ultra on purpose: the Ultra is faster but gives up surface quality (r/ElegooMars)
• The 36-LED COB source is cooled by a large fan, and the machine stays fairly quiet while printing (3DToday)
• Small footprint: 227×227×438 mm and 5.5 kg for a 153×78×175 mm build (3DToday)
• A USB air purifier with a carbon filter is in the box and clips under the cover behind the vat (3DToday)

Cons

• Anti-aliasing effectively doesn't work: the firmware only eats .goo files, where AA amplifies banding or kills the print — owners got worse surfaces than on a 2K Mars 2 (r/ElegooMars)
• No Wi-Fi and no network — USB sticks only, and picky ones: support recommends a sub-16 GB FAT32 drive (r/ElegooMars)
• A recurring power button and PCB fault makes the printer reboot at the start of a job; support ships a bypass or a new board (r/ElegooMars)
• Leveling is manual via two screws, and the LCD is a consumable with a 3-month warranty (3DToday, r/ElegooMars)

It suits home and hobby work: tabletop miniatures, busts, small functional parts and a first step into resin printing. If you need working anti-aliasing, network transfer or a tilting vat, look at the Mars 5 and Mars 5 Ultra.

Bottom line: cheap hardware with strong optics and weak software. Elegoo's own store lists it as sold out, so it's worth hunting only in leftover stock and with the .goo limitations in mind.

Reviews

• FauxHammer — Elegoo Mars 4 9K Review: Don't Believe THEIR LIES!
• r/ElegooMars — Mars 4 9K performing worse than Mars 2 2K due to anti-aliasing
• r/ElegooMars — First-time resin owner with a Mars 4 9K