The Formlabs Form 1+ ($3,299) is compact for a 3D printer, yet capable of producing objects at very high resolution. Its magnificent print quality makes it a great choice for product designers and other professionals. Although printing with the Form 1+ was more problematic than with the Ultimaker 2, our Editor's Choice 3D printer for makers and professionals, the results may be worth the extra work.

Design
This 3D printer measures 18 by 12 by 11 inches (HWD) and weighs 18 pounds. The build volume is modest (6.5 by 4.9 by 4.9 inches, HWD). It offers very high output resolution, at 25, 50, and 100 microns. Its coarsest resolution, 100 microns, is the same as the finest resolution of most of the 3D printers we've tested. A notable exception is the Ultimaker 2, which can print at resolutions as fine as 20 microns.

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The Form 1+ distinguishes itself in terms of the material and process it uses. While other 3D printers build objects out of successive layers of molten plastic filament in a process called fused filament fabrication (FFF), the Form 1+ uses a technique called stereolithography, which is actually the first 3D printing method to be developed. In stereolithography, an ultraviolet laser shines into a vat of UV-curable liquid resin, tracing a cross section of the object to be printed on the resin and in the process, solidifying it layer by layer into the printed model.

Stereolithography machines have traditionally been hugely expensive, with many running well into six figures. The past few years have seen great inroads in making this type of printer relatively more affordable, with the Form 1+ being a prime example.

Folks who got started in 3D printing by printing in plastic with FFF machines may be surprised by the Form 1+'s seemingly upside-down approach. The object grows out of the bottom of the build platform, which descends into and rises from the resin tray. It is a thing of wonder to watch as the object being printed slowly emerges from its vat of goo, with a greenish laser light flickering around it. The Form 1+'s cover is translucent orange, though not primarily for aesthetic reasons: It acts as a UV filter to help prevent the resin from accidentally curing and solidifying.

Setup and the Fine (Yet Onerous) Art of Finishing
Shipped along with the printer is a finishing kit, anchored by a four-chambered plastic tray. One chamber holds the build platform after an object has been printed. After a printout, the platform and object are then sticky with resin, and, hands protected by gloves, you have to pry the object off the platform with a provided scraper, place it in a rinse basket, and dunk it into a vat containing isopropyl (rubbing) alcohol. After the object has been immersed for about 20 minutes in two alcohol baths, you remove it and leave it out to dry.

After setting up the finishing kit, actually getting the printer up and running is easy enough. I downloaded and installed the company's PreForm software to my PC, turned the printer on, and connected it via USB cable to a computer. I poured resin into one of the tanks, slid the tank into its slot in the bottom of the printer, attached the build platform, and locked it into place. I launched the software, selected a file to be printed, resized and moved the object, which is shown on the PC screen, launched the print from the software, and pressed the Print button on the front of the printer.

Printing
I printed a number of test objects in both black and clear resin. Objects printed with clear resin have a beautiful translucent, almost glasslike sheen, and those printed with black resin were a pleasing, glossy black. The black objects were largely flawless, with most showing great detail and smoothness, even at the Form 1+'s lowest resolution. Due to a seemingly defective resin tray (more on this below), the first objects we printed with the clear resin were problematic. One had great detail, but with a lopsided base; another mostly pulled off of the supports meant to stabilize it and printed out bent as a result, and there were a few misprints thrown in. When the tray was replaced, object quality was much better.

The Care and Feeding of Resin
Dealing with the resin requires care. When adding resin to a tank, you need to be careful not to overfill it. Bubbles, which are frequently seen in freshly poured resin, can damage print jobs, as I found out; the bubbles should be smoothed out or the resin be allowed to settle for 30 minutes or so. Between print jobs, you need to run a scraper and comb through the tank to remove any hardened resin. Neglecting to do this can result in misprints, as I discovered in my testing.

The trays are the same translucent orange as the printer's cover, to minimize exposure to unwanted light. A single resin tray comes with the Form 1+, as well as a bottle of resin of the color of your choice. Using more than one color resin requires a separate tray ($59) for each, and two colors of resin shouldn't be mixed. When a resin tray is not in use, it should be covered with a plastic lid that comes with it, and stored away from light. You can keep leftover resin in the tray, but you should not pour it back into the bottle.

Resin trays need to be handled with care. According to Formlabs, it's not too unusual for a tray bottom (and its optical surface) to be inadvertently damaged by its user, necessitating the tray's replacement. My problem tray apparently was defective when we received it, which Formlabs says is unusual.