Once the random printing is finished and users are acquainted with the 3D printing process, the second stage of this phase is to start printing valuable items for the lab (Figure ). And here, the possibilities are endless. Most probably, the first useful things 3D printed in any laboratory are holders for every single vial, tube, and cuvette you have in the lab. There are plenty of designs, from NMR tube holders to magnetic-ready Eppendorf holders for magnetic separation, freely available online from repositories like Thingiverse, Printables, or the NIH 3D printing repository. If you need a holder for something, it has probably already been designed by someone else, and it is ready to be downloaded, sliced for 3D printing, and printed (Figure ). Even if you stop reading here, and your printer will only be used to print holders, you will already have the return on investment in a few months, considering how much sample holders cost.