Athletic apparel giant Under Armour (NYSE:UAA) used 3D Systems' (NYSE:DDD)selective laser-sintering technology to produce its UA Architech, the world's first performance training shoe with a 3D-printed midsole that's available to the general consumer market. This marks Triple D's second such victory in the burgeoning 3D-printed athletic-shoe space. In November, New Balance announced an exclusive partnership with 3D Systems to make the world's first running shoe with a 3D-printed midsole that will be commercially available.

First, a look at these two shoes, and then I'll discuss why 3D Systems' SLS tech is emerging as a winner in this space. 

Image source: Under Armour.

Under Armour's UA Architech 
Earlier this month, Under Armour introduced the UA Architech, which sports a 3D-printed lattice-structure midsole, and announced the shoe would be available in a limited edition of 96 pairs on March 18. Folks grabbed up the $300 shoes, which were sold out online before 7 a.m. EST that day, according to my check. The Baltimore-based company plans to release several other 3D-printed shoe models this year, and to launch customized 3D-printed shoes in the future.

Because the Architech is a multipurpose trainer, an athlete can use it to go from an exercise where stability is critical, such as weightlifting, to one where flexibility and a relatively light weight are key, such as running sprints. Under Armour's development process involved studying various geometric shapes and structures in nature and architecture -- hence the shoe's name -- to develop a midsole heel design that would be best suited for such a shoe.

Autodesk's (NASDAQ:ADSK)Within software was used to generatively design the lattice midsole, which is impossible to make using conventional manufacturing techniques. Generative design involves a computer algorithm generating structures based on criteria like durability, flexibility, and weight.

Under Armour apparently used 3D Systems' SLS technology for this initiative. I figured this was the case, because New Balance is using it to produce 3D-printed running shoes. There's no mention anywhere of the technology used to produce the trainers, but I spotted 3D Systems' printer in a Gizmodo video about this story.

Under Armour is likely using the printer on its own, because New Balance's press release in November indicated that it was exclusively collaborating with 3D Systems in its 3D-printed running-shoe efforts. "Exclusive," however, could just apply to 3D printing running shoes, rather than athletic shoes in general. 

Image source: New Balance.

New Balance's 3D-printed running shoes to launch in April 
New Balance announced last November that it was working in an exclusive collaboration with 3D Systems to 3D-print an elastomeric material into a honeycomb-like structure to form midsoles for running shoes. The team used 3D Systems' newly developed elastomeric powder, DuraForm Flex TPU, which was 3D-printed using SLS technology. Elastomers are polymers that are light and flexible, yet strong.

The midsole was designed based on underfoot pressure data from where the runner's foot strikes the surface, with more cushioning in areas of higher-than-average pressure. This project involved collaboration among experts in running and biomechanics, plastics engineering, material development, and generative design.

New Balance's limited-edition -- no word on the exact number -- 3D-printed running shoe will launch first in Boston in April to coincide with the Boston Marathon, and then in select New Balance retail locations around the world. The company reportedly plans to roll out customized versions in 2017, though it hasn't provided details.

3D Systems' S Pro SLS Center. Image source: 3D Systems.

Why 3D Systems' SLS technology is emerging a winner in this space 
Selective laser sintering allows for the production of some geometries that are impossible to produce by other 3D-printing technologies, such as stereolithography (SLA) and fused deposition modeling (FDM), let alone by conventional manufacturing methods. This is because the part being made is surrounded by unsintered powder at all times, so it doesn't need special support structures to fabricate overhanging designs. Additionally, because the SLS machine's chamber is always filled with powder material, multiple parts can be positioned to fit within it, making the process more cost-effective.

3D Systems had the patent lock on SLS technology until several key patents expired in 2014. So it's almost a sure thing that any company that's been using SLS technology in its 3D-printing efforts for a while is using a 3D Systems' model. 

Image source: Carbon3D.

It's looking like 3D-printed athletic shoes will be a big business in the relatively near future. 3D Systems needs to speed up its SLS technology if it wants to be a major player in mass-produced customized midsoles.

Investors should keep their eyes on start-up Carbon3D, which plans to launch a super-speedy 3D printer in 2016 that reportedly excels at producing elastomers. Carbon3D announced last spring that an unnamed "major athletic apparel" company was testing a 3D printer based on its Continuous Liquid Interface Production (CLIP) technology. I believe it's likely that Nike (my second guess is Under Armour) is the athletic-apparel company that's testing this printer for the production of midsoles for athletic shoes.

Autodesk's generative design technology is also worth a watch. If 3D printing for production purposes beyond small runs takes off -- and there's every reason to believe it will -- Autodesk Within software could be a considerable winner.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.