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SLA Comparison: Prusa SL1S Speed vs Formlabs Form 3

Prusa Research, the acclaimed RepRap FDM printer company, released the Original Prusa SL1S Speed this year. As an upgraded version of the Original Prusa SL1, their first attempt into the low-cost hobbyist SLA market, the new Prusa SL1S Speed offers …

Alejandro Auerbach

November 9, 2021

Prusa Research, the acclaimed RepRap FDM printer company, released the Original Prusa SL1S Speed this year. As an upgraded version of the Original Prusa SL1, their first attempt into the low-cost hobbyist SLA market, the new Prusa SL1S Speed offers a massive boost in comparison. Its new and improved features provide Prusa Research with enough means to reach the prosumer 3D printer market.

On the other side of this comparison, we have the Formlabs Form 3 model, the prosumer SLA of excellence, leading that same market flawlessly for many years now. So, how good are the latest Prusa Research innovations in this field? How do they compare to the Formlabs Form 3, a firmly established point of reference?

Prusa SL1S Speed

Prusa Research, the company known for the famed Prusa i3 series, its founder (Joseph Prusa) public persona and its open-source philosophy, took its first steps into SLA printing with the Prusa SL1 in 2018 after absorbing the SLA manufacturer, Futur3D. The SL1S Speed upgrades have set high expectations for Prusa to compete with previously established big names.

Why are these upgrades so relevant? And what are these upgrades in the first place? As the name implies, Prusa Research focused on print speed, aiming at two aspects: Tilting motion and curing exposure. Their characteristic tilt tank is now 2-4x faster than the previous version due to a shift from aluminium to reinforced PA6. The other is that they managed to shorten their exposure times after shifting from an RGB LCD display and a v-shape reflector to a monochrome screen and a new UV LED system. Overall, they managed to boost speeds up to three times faster than the previous model. Additionally, they added a 25% wider print platform.

Formlabs Form 3

Formlabs has had many years of a learning curve that led to what we have today: An optimal balance of quality, affordability, ease-of-use, workflow productivity, material versatility and a deep understanding of customers needs. All these years of development gave rise to their flagship product, the Form 3. This machine remains as the leading SLA solution in the market for small and big businesses alike since its release in 2019.

Its Low Force Stereolithography (LFS) technology leverages the benefits of a flexible tank, which remarkably solves one of the most significant issues SLAs commonly have: peeling forces. Therefore, the Form 3 delivers prints parts with extra detailed features, smoother surface finishes, and a better support contact point placement, enabling cleaner removals.

Comparison Side by Side

 Prusa SL1S SpeedFormlabs Form 3
SLA technologyMSLA (Masked Stereolithography)LFS (Low Force Stereolithography)
Light SourceMonochrome LCD and UV LED panelLight Processing Unit (LPU), 250 mW
Build Volume127 × 80 × 150 mm145 × 145 × 185 mm
Layer Heights25-100 µm25-300 µm
Supported MaterialsAny third party 405nm resinProprietary Formlabs Catalogue
XY Resolution50 µm (5.96” 2560×1620p screen)25 µm
SoftwareFull support in PrusaSlicerPreForm, Formlabs Dashboard
ConnectivityUSB, Wi-Fi, LAN, remote network interfaceUSB, Wi-Fi, LAN, remote network interface
Price£1450 (£1885 the complete package)£2900 (£4299 the complete package)
Bed LevelingAssistance wizardClosed-loop calibration

Quality / Speed

In 3D printing, quality and speed are always intrinsically related. Commonly an increase in speed causes the opposite effect on print quality. However, the opposite can also happen with stereolithography.

The Key is Peeling Forces

As we previously pointed out, peeling forces is a massive shortcoming for this technology. As the resin cures on the tank surface, the detaching action of the print platform can negatively affect the print layer while also delaying the process. 

Dealing with peel forces enables better and faster results and protects the useful life of the printer’s components. Both the Form 3 and SL1S offer brilliant solutions to this issue. So, how do they do it? On the one hand, the Form 3 uses Formlabs’ revolutionary LFS system. On the other hand, the SL1S uses a motorised tilt tank that ingeniously enables stirring without the need for additional components while subsequently adding a significant boost in speed.

Although the Prusa’s tilting system has its obvious advantages, the flexible tank of the Form 3 goes one step further. As the membrane adapts to the part’s geometry, translucent parts print clearer than ever. But perhaps, the best part is that it enables light-touch supports. As a result, supports are easier to pull while leaving fewer marks on the print’s surface.

Light Source

The other important aspect of stereolithography is its light source. While the SL1S uses the MSLA system, an LCD masked projector, the Form 3 uses the single spot SLA laser system. So, how does it affect quality and speed? The simple answer is that MSLA is faster than SLA because it can cure a whole layer at once. Nonetheless, when it comes to resolutions, this system is dependant on pixel sizes and, due to the squared shape of pixels, aliasing marks are inevitable in the final results. SLA smooth, on the contrary, can deliver more accurate results and smoother finishes.

When it comes to maximum XY resolutions, the SL1S offers an excellent 50 µm, which is decent among MSLA systems on the market. But, in the end, it falls short when you compare it to the Form 3’s 25 µm resolution.

Other Features

Sensors are essential to ensure quality and repeatability during the printing process. The SL1S has an excellent set of sensors, like, for example, the resin level sensor, which helps avoid spiling and pauses the printing process if the tank is empty. Comparatively, the Form 3, a machine specifically designed for business productivity, has sensors installed all around. One such example is the heated air circulation system, which enables the ideal chamber temperature control.

In the end, with under two seconds of layer exposure times, the SL1S is currently one of the fastest SLA printers in the market, far superior to the Form 3. But, the latter offers much better resolutions, precision and reliability.

Formlabs Form 3 SLA 3D Printer

Build Volumes

Build volume has always been a limitation for SLA machines, but the SL1S falls behind here compared to other stereolithography options (Even after expanding the original SL1 print platform). So, it’s kind of a disappointment that you can’t correctly leverage outstanding speeds to print large scale or multiple parts.  

The Form 3, on the other hand, offers a much more generous build volume (2.5 times larger than the SL1S). This is without even considering that the Form 3 build volume isn’t that large if you compare it to the Form 3L.


3D printing is not just about qualities and speeds but also about workflow features: Ease-of-use, streamlined process, automation, connectivity, interfaces, monitorisation and support. We can start with how the respective philosophies for each company influence workflows. Prusa Research is known for its open-source philosophy, while Formlabs maintains proprietary features.

Open Source vs Proprietary

For instance, the most recognisable difference is consumables. While the Form 3 only accepts Formlabs proprietary resin cartridges, the SL1S enables users to experiment with a broader set of third-party options. By being costlier and a more professional option than other Prusa products, the SL1S is a particular case. However, it still retains many aspects of typical DIY workflows.   

In contrast, the Form 3’s hands-off nature and streamlined ecosystem are widely possible thanks to their proprietary approach. With its wide array of sensors, this machine constantly monitors print performance, micromanaging every aspect of a print and ultimately sending you alerts.

Manual Pouring vs Cartridge System

While Prusa works with a manual resin pouring methodology, Formlabs goes with an auto-dispensing cartridge system. The manual pouring enables simplicity in contrast to dealing with a bulky cartridge. However, it is a much dirtier process with more risks of spilling despite having a resin level sensor. If you sum the small size of the vat with the tilting mechanism, the 100% volume mark is relatively low, allowing for only 200ml of resin at a time. Alternatively, the Form 3 manages your resin levels for many prints and enables you to know when to change them swiftly.

Scaling Production

Formlabs’ product ecosystem is geared towards productivity, teamwork, and enterprise friendliness since hardware, software, and materials are seamlessly working together. So, it’s easy to deploy and manage a fleet of Formlabs 3D printers. Formlabs’ modular scalability is a great advantage over the SL1S if you need to manage a larger production efficiently.

Software: Slicing and Remote Management

Let’s start with their respective slicers. PrusaSlicer, the same slicer Prusa offers for FDM printing, smartly adapts SLA slicing with hollowing and automatic support generation settings. Additionally, they offer a library of factory-tested profiles for countless resins. Formlabs Preform, on the contrary, has a long history of simplifying the preparation process into a fast but effective one-click printing.

Regarding remote workflows, the SL1S is linked to the Prusa Connect Local, an OctoPrint-like interface. In this field, Formlabs Dashboard goes steps further since this web-based interface is tailored for enterprise workflows. Dashboard offers remote printing, print job status, user access system, timelines, and supply management, among its many features.

Last Thoughts

Although both printers are intended for professionals, the Form 3 leans more towards enterprise productivity, scalability and industrial applications, while the SL1S still retains some of the aspects of DIY printers in the hobbyist market.

As the name promises, the Original Prusa SL1S Speed delivers unprecedented speeds, but only at small scales, and it requires further tweaking and manual intervention than the Form 3. In contrast, the Formlabs Form 3, despite not being as fast, is part of an ideal 3D printing ecosystem, granting users smoothness and ultimate confidence in their processes.

To get top-notch advice on SLA products, SolidPrint is here to help. Call SolidPrint at 01926 333 777 or email

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