One of the things you’re paying for when you buy a 3D printer from Prusa Research is, essentially, your next 3D printer. That’s because Prusa’s machines are designed to be upgraded and modified as time goes on. An upgrade kit is always released to allow each older printer to be converted into its successor, and while there’s occasionally been some debate about whether or not it’s the most cost-effective choice, at least it is a choice you have as an owner.

If you’ve got a Prusa MK4, you’ll soon get to make that decision for yourself. Announced earlier today, the new MK4S brings some notable changes to last year’s printer. The $99 upgrade is scheduled to be available by the end of the month for existing owners, but if you’ve been on the fence about joining Team Orange and Black, you can purchase the MK4S right now in both kit and assembled forms for the same price ($799 and $1,099 respectively) as the previous MK4.

So, what’s new with the MK4S? With speed an increasingly hot topic in the 3D printing community, it should come as little surprise to find this new machine is even faster than its predecessor. A reworked cooling system and new high-flow nozzle mean Prusa’s latest can spit out everyone’s favorite little boat in 14 minutes—or as little as 8 minutes if you don’t mind a slight drop in print quality.

The announcement post also cites improvements to the machine’s printed structural components. Parts that were previously made in PETG are now being printed in carbon fiber-infused polycarbonate. Some parts, such as the front panel, have even been switched over to injection molding.

While describing the changes made with the MK4s, the blog post also clarified Prusa’s position regarding open sourcing of their printers. There was considerable concern back in March of 2023 when the company announced it was reconsidering its traditional dedication to making its hardware and software as open — as much as possible — in light of increased commercial competition. But now the company has posted a chart on their site that explains not only what’s being shared for each of their printers, but a timeline as to when we can expect it.

While it hasn’t been updated for the 4S yet, the overview shows that the company plans on holding onto the design files for the MK4 PCBs until the end of the product’s life. Otherwise, it seems their current flagship printer is equally as open as the MK3 that came before it. While a time-limited source release will likely rub some in the wrong way, the reality is that it’s more than you’d get with pretty much any other 3D printer manufacturer out there.

The announcement also talks briefly about the new GPIO “Hackerboard” that the company will start shipping in September. The $15 board plugs into an expansion connector on the PCB of the MK4 or MK4S, and provides eight pins that can be toggled via G-Code sent to the printer. These could be used for all sorts of automation tasks, such as turning on the lights and fans inside of an enclosure or triggering the shutter on a camera. There’s not much detail about this particular add-on yet, but it’s certainly something we’ll be keeping a close eye on.