## 1 Introduction  
Fused filament fabrication (FFF) printers are an increasingly common sight in laboratories around the world where a wide range of available feedstock materials, low machine costs, quick printing times, and material processing characteristics similar to conventional extrusion have become highly desirable in facilitating day-to-day research and development [1]. Whilst the majority of machines are for support, there is a growing transition to move FFF from a tool for prototyping parts [2, 3] to a fully-fledged manufacturing technique in its own right [4]. FFF printing has allowed innovation across a broad range of fields. For example, tissue support meshes created by [PERSON] et al. harness extrusion 3D printing processes to aid patient recovery [5], and shape-changing components designed by [PERSON] et al. implement 4D printing and shape memory polymer multi-materials to create structures that dynamically respond to thermal stimulus [6]. The production of custom microfluidic devices perhaps exemplifies the potential of tailored FFF, incorporating rapid fabrication times and flexibility of design whilst maintaining functionality [7, 8, 9, 10]. The ease by which complex shapes can be modelled and fabricated using FFF is of growing interest in tissue engineering, where extruded polymers can be used to produced scaffolds [11, 12]. PLA filament can be blended or mixed with additional biomaterials components such as chitosan [13], antibacterial alloys [14], lignin [15], structural metals [16], and hydroxyapatite [17, 18, 19]. The ability to extrude controllable thin depositions is desirable in tissue engineering, where 3D-printed meshes have recently been used to improve the mechanical properties of electrospun biomaterial scaffolds [20]. The generation of reproducible thin mesh structures would be of interest in biomedical engineering and in the pursuit of controlling localised cell interaction through printing microfeatures. FFF printing, however, inhabits a fairly narrow macroscopic scale. Larger, high-resolution parts (such as those with a volume over 100 cm\({}^{3}\)) may take too long to print for FFF to be considered a viable production method. Despite being the most popular 3D printing method available, the development of microscale FFF is limited [21]. Direct ink writing (DIW) has inspired work on microextrusion with some success, with fine PDMS line widths of 10 \(\upmu\)m achieved [22]. However, the optimisation of such printing is highly involved, printing is slow and of questionable scalability. Microextrusion is unsuitable at the mixed scale to, for example, embed microscale features inside the bulk of a macroscopic part or incorporate surface microtopographies. This issue of scalability is reflected in cost, as requiring the purchase of a specific printer to make thin structures is prohibitive to research. These units are not widely available and are therefore of little use to researchers seeking thin structures to complement their work. Access to conventional FFF printers, however, is likely to be available in most facilities. In FFF printing, first layer consistency represents a significant barrier in decreasing part size and enabling a reasonable comparison of structures printed on different printers. It is surprising then that many studies overlook the importance of reporting the calibration of their machines. In general, a preprinting calibration might involve:  
* Levelling of the print bed;
* Levelling of the extruder;
* Adjustment of the z offset (calibrating the 'zero point' between the nozzle and bed);
* Optimising the 'First Layer'. The specifics vary by printer manufacturer but these main points are broadly consistent. Print beds or surfaces are manually [23] or automatically [24] aligned to ensure that the distance between the nozzle and the printing surface does not vary across the bed and that the nozzle is 'zeroed'.