Data for 3D printing enlarged museum specimens for the visually impaired

Museums are embracing new technologies and one of these is the use of 3D printing. 3D printing allows for creating physical replicas of items which may, due to great value or significance, not be handled by the public, or which are too small or fragile to be handled or even seen with the naked eye. One such application of new technologies has been welcomed by the National Museum in Bloemfontein, Free State, South Africa. Here, blown-up (enlarged) Museum specimens were 3D printed for various interactive exhibits that are aimed at increasing the accessibility of their permanent displays for visually impaired visitors who rely greatly on touch as a source of observation. A selection of scorpions, pseudoscorpions, mites and archetypal bird skulls were scanned, processed and 3D printed to produce enlarged, highly functional nylon models. This data paper provides the raw micro Computed Tomography (micro-CT) scan data and print ready STL files processed from this data. The STL files may be used in their current format and details of the printing are provided.


INTRODUCTION
In general the use of 3D printed models for museum displays or research has been positively received as evidenced by numerous publications and in some instances, a preference for 3D printed models was indicated [1,2]. The use of micro Computed Tomography (micro-CT) in biological sciences was reviewed in [3] which also includes data sets of a Jackson's chameleon with 3D print files [4]. The use of micro-CT and 3D printing has been used successfully for non-invasive investigations as in [5,6] where 3D print replicas of the contents of an Egyptian mummified falcon were reproduced successfully.

MATERIALS AND METHODS
MicroCT and nanoCT scans were conducted at the Stellenbosch CT facility [7]. The smallest samples were scanned in the nanoCT and samples > 10 mm wide were scanned in the microCT instruments using optimized settings and voxel sizes appropriate to each sample. Image data was analyzed in Volume Graphics VGSTUDIO MAX 3.2 (VG Studio MAX, RRID:SCR_017997). A de-noising was applied, followed by a surface determination function. In cases of noisy data, some cleanup was done according to visual inspection using morphological image tools (erode/dilate and region growing). The final STL (stereolithography) files were then processed in Materialise Magics (23.0.1.19 64 bit) software to remove loose shells and reduce the number of triangles to ensure clean 3D models that can easily be scaled to any specific requirement.
The clean 3D models were produced in an EOS P385 Selective Laser Sintering system in white PA2200 Polyamide (Nylon) powder.

DATA
Photos of the final 3D printed objects are shown in Figure 1 with a comparative visual of a larger scorpion specimen in the three stages of the replication process found in Figure 2. The CT data is provided in the form of image stacks with associated voxel size and other scan settings in the accompanying text file. The processed STL files used for printing are also provided with each scan data set and can be viewed with any 3D model viewer The summary of all data provided is given in Table 1. Interactive views of the 3D models are available in the sketchfab repository, which enables CT images to be interactively explored. Figure 3 provides an example of an interactive CT sketchfab view of the Opistophthalmus carinatus specimen.
Creating these 3D models enabled the National Museum in Bloemfontein to create a new type of exhibit, where visually-impaired visitors can handle the 3D printed replicas to better understand the specimens that previously they could only learn about through verbal or written descriptions (Figure 4). Creating and having these resources increases the accessibility of the museum's information to a broader community than was previously served.   CONCLUSIONS This data will be useful for Museums setting up similar display. In addition to museum activities, these data can also be used for other research purposes that require material that cannot transported or shared. The workflow may also be useful for these and similar projects, and we urge others having similar types of data to make it openly available as well.

DATA AVAILABILITY
All the data including CT scan details, 3D surface rendered images in STL format, and interactive views of the 3D models are available in the associated GigaDB dataset [8]. 3D models are also available for view in Sketchfab (https: