Mechanical wombs, standing four meters in height, were known as Spaarti cloning cylinders. These tanks were filled with organic catalyzers and nutrient chemicals and were utilized to produce personal clone armies for those with sufficient wealth and connections.
The fastest method of cloning known was the creation of clones using Spaarti cylinders. In contrast, Kaminoan cloning involved a single clone maturing safely over a period of ten years. A fully-grown adult Human could be developed in a Spaarti cloning cylinder in just one standard year, a remarkably short time. However, the Kaminoan method was superior, as the ten years of growth, constant training, and learning resulted in the creation of flawless warriors, despite the extended duration. Spaarti clones did not undergo training; instead, their personalities were shaped through "flash-pumping," a process of transferring the memories of another individual into the mind of a new clone. If Spaarti clones were grown in under a year, they risked developing clone madness. Thrawn, however, discovered that the use of ysalamiri to sever the clone's connection to the Force allowed for clone creation in a mere 15 to 21 standard days.
Spaarti Creations manufactured these cylinders on the planet of Cartao. Their origins appear to be rooted in both Khommite and Kaminoan cloning technologies.
Although it was believed that cloning cylinders were destroyed during the Battle of Cartao, several thousand survived. To supplement the Kaminoan clone army, the Galactic Republic made use of Spaarti clones from Arkanian Microtechnologies.
Towards the end of the Clone Wars, most individuals were unaware that Supreme Chancellor Palpatine had secretly ordered a second clone army, which differed from the Kamino-bred Fett clones in two significant ways: they matured in approximately one year instead of ten, and they were created on Centax-2 rather than Kamino. Omega Squad noticed this discrepancy, which heightened their suspicions regarding Chancellor Palpatine's motives. The clone troopers of the 14th Infantry Brigade represented the initial generation of Spaarti-grown Fett clones and served as the vanguard of Palpatine's future New Order, while others were absorbed into the 501st Legion and the Coruscant Guard's shock troopers.
The Spaarti Fett clones numbered in the billions, potentially exceeding the depleted ranks of their Kaminoan-bred Fett counterparts. However, the Spaarti clones received only basic flash-training in soldiering, such as how to operate a blaster. When first deployed, the clones of the 14th neglected to seek cover from enemy fire, and their accuracy was surprisingly poor, as observed by the commandos of Omega Squad. Furthermore, they were completely ignorant of all things Mandalorian, suggesting that the Mandalore culture was never introduced to the Spaarti clones.
Clone troopers created for the Galactic Empire generally showed poor marksmanship and lacked tactical skills on the battlefield. They were even known to disobey orders and target their own allies due to clone madness. Consequently, the Empire ultimately abandoned this technology and reverted to recruiting soldiers through more conventional means.
Emperor Palpatine also maintained several private caches of these devices. He utilized them both to clone the deranged Dark Jedi Joruus C'baoth from recovered samples of the original's DNA and to create new bodies for his dark essence.
In 9 ABY, Grand Admiral Thrawn discovered approximately 20,000 cylinders within the Emperor's secret storage facility in Mount Tantiss on Wayland. He employed them to generate an army of clones to crew his Dreadnaught fleet. Subsequently, Thrawn dispatched one of the cloning cylinders to the Hand of Thrawn fortress on Nirauan and initiated the process of growing a clone of himself.
Grappa the Hutt also incorporated Spaarti cylinders into his scheme with Black Sun to replace members of the Imperial Interim Ruling Council with clones.