## 2 Materials and Method
### Data Collection and Analysis  
Prior to CT imaging, the mass of each sample was measured using an analytical balance, Weightlab WSA-224 (Weightlab Instruments, Istanbul, Turkey), with a sensitivity of 100 \(\upmu\)g (Figure 3). Accordingly, the physical densities of the samples were calculated and recorded.  
Figure 2: Cylindrical samples were both printed at 250 \({}^{\circ}\)C and 100% flow rate. The LW-PLA sample (left) exhibited overexpression due to excess flow, resulting in an unintended geometry of the print job.  
After determining their densities, the printed samples were affixed to PMMA disks, which were designed and fabricated before, as in Figure 4a. Subsequently, these disks were positioned within a cylindrical PMMA housing, characterized by its 0.5 mm thick walls, 15 cm inner diameter, and 30 cm length (Figure 4b). The bottom plate of the housing was securely affixed with silicone, while the top plate was designed to be remountable, utilizing a liquid seal and four screws. To ensure stability during horizontal scanning, a pair of support materials was thoughtfully designed. Distilled water was introduced into the housing to establish the 'water phantom', as illustrated in Figure 4c.  
Figure 4: Printed samples mounted on PMMA disks (**a**), which were placed in a water phantom (**b**) prior to a CT scan (**c**).  
Figure 3: All of the samples weighed using Weightlab WSA-224 analytical balance.  
The water phantom has been imaged using a 128-slice Philips Ingenuity CT scanner. Imaging protocol includes a tube voltage of 120 kVp and effective tube current-time product of 310 mAs. The reconstructed slice thickness was 0.4 mm with a collimation of 64 \(\times\) 0.625 mm per rotation. CTDI\({}_{\text{vol}}\) was recorded as 20.3 mGy in the body phantom, while SSDE was 46.1 mGy. The image reconstruction diameter, namely field of view (FOV), was 250 mm with a 512 \(\times\) 512 matrix, resulting in a pixel size of 0.488 \(\times\) 0.488 mm\({}^{2}\).  
Following the CT scan, the CT image was loaded into imQuest, a practical CT image analysis tool developed by Duke University and made available online [27]. Data collection involved drawing circular regions of interest (ROIs) with a diameter of 1 cm on 30 consecutive axial slices in the central portion of each sample. Mean HU values and their standard deviations (STDs) were recorded for every slice, as illustrated in Figure 5, and then averaged over the 30 slices. Additionally, the standard deviation of the mean HU values was calculated as a measure of the homogeneity along the longitudinal axis. For simplicity, the average of the axial STD values is referred to as STD\({}_{\text{xy}}\) notation, while STD\({}_{\text{z}}\) is used for the STD of the mean HU values across the 30 slices.  
The reproducibility of the samples was analyzed by averaging the mean Hounsfield Unit (HU) values obtained from three consecutive identical printing jobs and calculating the standard deviation across them. On the other hand, one-way ANOVA tests were performed to analyze the differences among the mean HU and STD\({}_{\text{xy}}\) values obtained from the sample groups with diameters of 1.5 cm, 3.5 cm, and 5.5 cm. Subsequent tests, such as Tukey  
Figure 5: The mean Hounsfield Unit (HU) and standard deviation (STD) were measured by drawing circular regions of interest (ROIs) with a diameter of 1 cm at the center of each cylindrical sample, as well as within water, across 30 consecutive slices.  
and Tamhane, were conducted to identify the specific group or groups responsible for the observed differences.