technically, it depends on what if any rights/permissions are explicitly conveyed by the actual author/owner/copyright-holder
all of my files come in a .zip file with a limited license to reproduce the work but not to redistribute the work - which means you can make physical decorative items for sale but you may not share the work or any derivative with 3rd parties or otherwise permit, enable or allow 3rd parties to obtain or reproduce the work by any means other than the same way you acquired that right by registering and downloading from here and complying with the license agreement which specifically prohibits using the work in logos, trademarks, or other non-decorative business uses
additional restrictions may apply if, for example, the work is a trademark then it is the intellectual property of the respective mark owner and should only be used in compliance with trademark law or some other explicit agreement with the mark owner
in the abscence of any such explicit permission/license it is up to you to know or determine whether it would be 'legal' to reproduce any given artwork regardless of where, how, or from who you obtain it - in other words, just because someone posts something so you can download it does not in and of itself convey any assumed right to reproduce - especially if the poster is not the author or primary intellectual property rights owner of the work in question
one should be especially cautious about commercial use of any potentially commercial artwork for cutting that is shared for cutting without knowledge or permission of the commercial-artist/business that developed the art to sell or for publicity - even if you unknowingly exploit the intellectual property of another business - there can be very serious consequences and almost no viable defense if the actual rights owner can determine that you are using their work unlawfully, without explicit permission, or outside of compliance with any actual license to use any given artwork or trademark - that harms their business and there are ways they can make you pay dearly - in my case it automatically and immediately terminates all license to use any signtorch artwork or products
