This work is focused on the additive manufacturing (AM) of Fused Deposition Modelling (FDM) technique that is in full growth and development. 3D printing is a technology that has a great impact nowadays in industrial field for its innovation in the rapid industrial prototype (RP) as well as in the area amateur to the houses for its simplicity to carry out any idea that it can be in mind. And it is very efficient in terms of do-it-yourself (DIY) projects or for lucrative purposes. Being a recent technology, and with such a large expansion in the two areas discussed above, this work has focused on comparing the quality and accuracy of two 3D printers of FDM technology (each one used in a different field) of high prices distant through the ISO grades of ISO 286-1:2010. To carry out this project, a 3D DIY printer has been obtained and it has been assembled and has been compared to a professional printer. To make the comparison a test with pieces of different diameters has been designed that has allowed us to evaluate the precision in a range of optimum sizes. Subsequently, the results were analysed and it has been obtained their IT grade for each printer in each range of sizes.