This has come up a couple of times, but not recently.
In theory if you don't actually copy something in order to re-purpose it then you wouldn't be infringing copyright. This is because of something called exhaustion of rights
. Briefly this doctrine says that once an item which is subject to copyright has been lawfully sold or given away, the copyright owner has no further rights in that specific item, provided that the sale etc was not subject to some form of licence by which the copyright owner retained some of their rights. An example of this occurs with End User Licence Agreements which frequently used to accompany software on CD/DVD*. Another example is that of movies on dvd or BluRay etc where the distributor may stipulate that the product is for home entertainment only and it may not be used for commercial rental.
However the sort of works you mention are rarely sold with any restrictions like EULAs and so the exhaustion of rights doctrine should be applicable to what you want to do. That's the theory. However, four years ago the Court of Justice of the European Union came out with a rather unexpected judgment which called this situation into question in one specific instance of re-purposing. The case was Art&AllPosters v Stichting Pictoright
[CJEU C-419/13]. Briefly this concerned a company which produced normal paper posters of, amongst other things, paintings. They did this legally under licence from Stichting Pictoright which is a body which represents artists in the Netherlands. The company then began selling the same poster images which they transferred via a chemical process onto canvas so that the new product looked as if it was painted on the canvas. Pictoright objected saying that this infringed the artists' rights to authorise reproductions of their works in different media, The CJEU agreed with the claimants Pictoright, saying that because the medium carrying the image (the paper in the poster) was replaced by another medium (the canvas) a new work was thereby created and so the exhaustion of rights doctrine did not apply. This decision has been criticised on the grounds that the CJEU were making new law which was not really supported by the existing Directives and thereby created uncertainty. And of course it only applies to this rather specific process of image transfer.
Nontheless the AllPosters decision is seen as watering down the doctrine of exhaustion of rights and certainly it makes the law less clear-cut on the issue. Given that you do not, I assume, intend to alter the actual medium on which your found objects are printed, I don't think the AllPosters decision should affect you.
There is just one other thing to bear in mind. Under UK law
(and that of the other EU member states) an author of a copyright work has a moral right for his work not to be treated in a derogatory way which prejudices his honour and reputation. This right (often referred to as the droit de l'intégrité
) is treated with far more respect in most other European countries, especially France, Germany and Italy, where even the slightest alteration or defacement of a work can been seen as a slight on the honour of the author or artist concerned. In the UK it would take quite a lot of derogatory treatment for a court to side with the author or artist, and so this is probably not something you need to be too concerned about.
* Software which is downloaded, along with other digital transfers like music downloads or ebooks etc, are not usually subject to the exhaustion of rights doctrine because they have no material form.