## 1 Introduction  
Additive manufacturing, otherwise known as three-dimensional (3D) printing, is a rapidly growing technology whereby products are built on a layer-by-layer concept [1, 2]. In many industrial fields, 3D printing has become central in product manufacturing since new shapes and prototypes can be realized after a suitable digital design. In recent decades, several advances have enabled the 3D printing of biocompatible materials together with cells (bioinks) to produce complex 3D functional living-tissue-like constructs [3, 4]. In this case, biocompatible materials such as hydrogels are used as printable elements instead of the plastic materials that are normally used for 3D printing. The bioink used to print cells consists of living cells, biocompatible biomaterials and/or active biomolecules [5]. Due to these characteristics, bioprinting holds the promise of establishing systems that more closely mimic human in vivo microenvironments than current two-dimensional (2D) cell culture environments, filling the gap between 2D and animal models [6; 7]. In the world, many researchers are working to adapt techniques and materials to the 3D bioprinting of cell models and tissues to be used in the field of tissue engineering and regenerative medicine, which is a key area in the biomedicine of the future. Nevertheless, while it is capable of creating new 3D cell models to answer many biological questions, the technology has remained inaccessible to most research labs due to the high price of commercially available bioprinters (USD 100,000-200,000) and low customization capacity, making it difficult for research groups to enter the field of bioprinting [8]. Three-dimensional bioprinting is mainly based on three approaches: extrusion-, droplet- or laser-based bioprinting. Extrusion-based bioprinters, which are derived from inkjet printers, are the most commonly used type of printers for biological applications, and are designed for the high-precision deposition of bioinks [9]. The main techniques in extrusion bioprinting use valve-based pneumatic or gear-driven actuator extrusion systems to drive cell suspensions out of a suitable needle tip. The current professional bioprinters enable high-precision results by providing a sterile environment and cell-compatible printing conditions but with high overall costs. What is currently missing is a range of low-cost bioprinters to approach bioprinting techniques for simple applications. Theoretically, 3D printing and bioprinting processes are based on the same printing principle: laying down materials or bioinks layer by layer in order to build a previously digitally designed 3D construct. Nevertheless, when bioinks are used, there are many problems to be considered; first of all, cell survival must be ensured in a bioprinting construct. For example, some researches have reported that the dispenser orifice size (150 \(\mu\)m) and the extrusion rate are fundamental parameters to consider for cell survival since they can control the mechanical stress to which the cells are subjected [10]. To date, several studies have been carried out to try to adapt commercial 3D printers to biological purposes [11; 12; 13; 14]. The use of commercial and low-cost 3D printers, modified for biological and medical research, allows for a great deal of freedom of maneuver to investigate specific objectives, including different printing methods, materials and the impact of environmental conditions on cells. However, to better evaluate the possibility of using commercial 3D printers instead of professional bioprinters for biological and medical applications, some features of the printing process have to be compared. This study describes the implementation of a commercial 3D printer to obtain a 3D bioprinter and benchmarks its performance against a professional bioprinting tool taken as a reference. We also demonstrate that this bioprinter can be used to print a construct model of a vascularized medulloblastoma tumor (MB).