Investors are polarized regarding the future of the emerging 3D printing industry. Those bullish on industry leaders Stratasys Ltd. (SSYS) and 3D Systems Corp. (DDD) find the 3D printing market a favorable long-term investment as engineers, designers, architects and entrepreneurs increasingly bank on 3D solutions for their design and product modeling. According to Wohlers Report 2014, the global 3D printing industry will boom from $3.07 billion in total revenue in 2013 to $12.8 billion by 2018, exceeding $21 billion in worldwide revenue by 2020. (See also: What Happened to the 3D Printing Revolution? (SSYS, XONE).

While the two largest and most diversified 3D printing industry leaders now publicly trade at a price less than five years ago, investors who see the industry maturing after a slowdown and debilitating lengthened sales cycle seek to buy. Further, tech vet HP Inc. (HPQ) is shaking up the industry with its expansion from 2D printing to 3D printing technology, enabling it to compete with a growing number of industry players.

1. Stratasys Ltd.

The Delaware-based technology company was formed in 2012 as a result of the merger between additive manufacturing companies Stratasys Inc. and Objet Ltd. In the second quarter, Stratasys reported a 19% decline in 3D printer revenue year-over-year (YOY), while print materials and customer support revenue were both up 11%. Adjusted earnings per share (EPS) came in at $0.12, down from $0.15.

Stratasys also recently entered a strategic partnership with Boeing Co (BA), Ford Motor Co. (F) and Siemens to introduce advanced 3D printing technologies to the aerospace and automotive industries. Along with the new alliances, Stratasys has launched two new products, the Infinite-Build 3D Demonstrator and the Robotic Composite 3D Demonstrator, to help users reduce complexities and data loss.

2. 3D Systems Corporation

 The South Carolina-based competitor of Stratasys boasts seven models as opposed to three, with the additional ability to print on materials other than polymers, such as metals and ceramics. While reporting a 7% YOY decline in revenue, the company saw its share price spike 18%. The reason behind this stock surge comes from the fact that EPS in the second quarter of 2016 broke through the roof of expectations. 3D Systems’ reported Q2 2016 earnings of $0.12 per share reflected four times last year’s Q2 EPS and doubled that of Wall Street’s projections. (See also: 3D Systems Shares Soar on Earnings Beat.)

3. HP Inc.

The emergence of tech industry giant HP in the 3D printing space could present a potential threat to smaller industry players such as 3D Systems and Stratasys. HP Inc. announced in May that it will enter the market with two separate models aimed at the industrial market, targeting companies that can afford premium high-capacity equipment. HP’s fiscal 2016 total revenue of $11.9 billion represented a 4% decline YOY, yet exceeded expectations of just $11.47 billion. HP stock is trading near the 52-week high of $14.82 and target price of $15, at $14.40 on Sept. 1.