So, both of the objects are meshes.
The text is hollow, 0,5mm walls.
When I choose the cube and go Boolean -> UNION - the cube disappears and the bottom of the text gets filled.
When I choose the text and go Boolean -> UNION - it simply does nothing.
I have just tried with a sample of text made directly in Blender and boolean works as it should.
The text “homemade” however is imported from Inkscape as SVG, so my guess would be that the problem is there, Im just asking here before I continue since Im stuck on this.
No blend file included in your post, only a tiny screenshot.
Please always supply a demo blend file for review for support questions. You can attache to the post or upload to http://www.pasteall.org/blend/ and supply the download link
Imported SVGs converted to meshes often have duplicate vertices and other mesh oddities that cause boolean operations to fail. Make sure object scaling is applied (ctrl-A in object mode) and remove duplicate vertices (in edit mode select all, W>Remove Doubles).
So is there a way to create the letters as they are now (hollow) but also to get them to work with the boolean modifier?
Cause after I export the STL I need to convert it to g-code for printing and I need the converter to see the letters as hollow shells so it does not fill them.