<p>The development of new analytical tools remains a powerful approach in analytical chemistry, and three-dimensional (3D) printing has gained increasing popularity as a manufacturing technique in recent years. The fabrication of experimental tools using 3D printers has attracted attention in many fields. However, objects fabricated by fused filament fabrication (FFF) may contain gaps between printed paths, and which can cause leakage when liquid is introduced. In this study, solvent-based post-processing was performed in order to fill layer gaps in FFF-printed polypropylene fluidic chips. As methods, a compression process and solvent-based post-processing were applied. In the compression process, a polypropylene fluidic chip was compressed using a compression tool while being heated. After this compression process, solvent-based post-processing was conducted. The post-processed chip was used to measure peak profile during flow-injection measurement. As a result, peak profiles were obtained, and no leakage from the chip was observed during the measurements.</p> Graphical abstract <p></p>