3D printing, I want in $DDD $SSYS

I read Ark Invest's Big Ideas for 2021 and according to them DDD and SSYS are the leading companies of the industry. As you can see in this chart, there is a clear winner when it comes of ROE, but I'll be buying the first one that plays by my rules. At the moment DDD is ranked 3rd in its group by IBD Investors and SSYS is ranked 4rd. Both are having a pretty heavy pullback that I intend to capitalize. Patience is the key, is better to get in late than early.

Although, DM is ranked 1st in the same group so, is worth to take a look at.