This model is about 42.2cm (16.6 inches) long. Is has opening payload bay doors, moveable flaps and speed brake. I couldn't think of anything to put in the PL bay, so it is empty. I took inspiration from Martin Taichl (https://www.printables.com/@Martin) and attempted to make this model as a kit with no glue required. I also designed the parts to reduce, if not eliminate, the need to paint - the main reason I purchased the Bambu X1-C.

First, let me say I printed this with a Bambu X1-C printer using PLA as the main filament with PETG as the interface between the part and support. If you have multi-filament capability, then I highly suggest using the PLA and PETG in this manner. For all pieces I used a 0.04 mm nozzle, but I had issues with printing the Boeing and Air Force logos (specifically the very small red stripe).

I split the model into four sections: the wing, payload bay, the aft section, and the forward section.

Now, to discuss how I put the model together assuming you print and put together the parts in this order. Starting with the wing section. Print the wings (wing left and wing right), the flaps (left and right), the pins for the flaps (one short, one longer – 2 for each wing half), and the spacer for the pins (2).

So, first printing the wing section. I suggest you use dark filament (I used “space grey”) for the wing halves to simulate the thermal protection system (TPS) material on the X-37B. I save printing in black for the nose tip, nozzle, and the connectors on the back surface – but more on that later. My slicer (Bambu Studio) suggested I print the wing horizontal but that resulted in some rough areas inside the cavity for the flap. While you cannot see this area when assembled, I decided to print it vertical, and the print was much cleaner. I will note however that printing a single wing (with supports) in the vertical orientation took 6 ½ hours and horizontally it took 2 ½ hours. Next, I printed the flaps. As suggested by the slicer I printed these vertically. The two holes in each flap are different depths. I would suggest orienting the flap, so the short hole (narrower outboard end) is at the bottom even though this makes the narrower outboard edge on the print plate and the wider edge up. I suggest at least a 5mm brim. I had no issues but if this still fails, then I suggest reorienting, so the wider edge is on the print plate (still use brim). The outboard edge being on the print plate makes it easier to remove the support filament inside the hole. Then print the pins and the spacers. For the pins and spacers, again, I suggest printing with at least 5mm of brim around the bottom to help with adhesion during the print. I also suggest that when printing all the ‘bags’ for connecting left/right halves you use at least a 5mm brim.

Assembly of wings: After removing all support material, just insert the flap, with short hole side outboard, into the wing cavity, and insert the pins. This should result in a movable wing, about +/- 15 degrees. I designed the fit to be tight but just in case I added the spacer to insert against the inside pin. When installed the spacer should be smooth or slightly inside the wing inside edge. This prevents the pin working its way out and you having to disassemble to correct. If you ever want to disassemble the wings and flaps, then I suggest not installing the short outboard pins. It is very hard to remove once installed. The flap will work sufficiently without the outboard pin because of the tight tolerances. Same procedure for second wing half.

Next, print the wing top. With this I suggest white filament for the part and black filament for the lettering. You print the wing top horizontally which lets you change the filament to black for the raised ‘USAF’ lettering if you do not have multi-filament capability. The wing top will secure the two wing halves together.

Next is the mid-body, or payload (PL) bay section. All this, I suggest you print this in white filament. You print the PL bottom sections horizontally, and the PL doors and the pivot rods vertically. The four pivot rods may need brim at bottom to support adhesion. After removing support filament, the assembly is straight forward. I suggest being very careful removing support from inside the rod holes in both the bottoms and the doors, so as not to break sides of the bottom section. Before final installation of the pivot rods into the PL doors, if you want to test the movement of the PL doors then instead of inserting the pivot rod (difficult, but not impossible, to remove once installed) use a length of the 1.75mm filament as temporary rods. This is a looser fit, but this allows the verification of the doors' rotational movement. Once each half is assembled then adding the two “bags” will allow the two halves to mate together. Now, the PL bay will mate onto the wing section.

The logo panels require additional discussion.

For the logo panels there has been some issue with the thin lettering and Air Force logo white star and red stripes. You have several options for printing. One option includes printing just the ‘USAF’ on the panels without the logos. I will include those panels as options. The thin lettering may not come out with a 0.4mm nozzle. I used the Arachne wall generator and had success with the ‘BOEING’ lettering, and I had no issue with the ‘USAF’ lettering. Another option suggests you print the panels in the vertical orientation with brim support. This resolves the letter thickness issues but printing vertically with a multi-filament/muti-color will greatly increase the flush volume and the time to print (3g for both panels, 52g flushed, 20g for tower totaling 75grams – and it takes over 7 hours on by X1-C). To help with the red stripes, I modified the Air Force logo’s red stripe to have separation between the adjacent stripes and that improved the printing. If you have access to a 0.2mm nozzle then you can print the panels horizontally with the logos. However, in the end, the Air Force logo is particularly hard to print with the red stripe. Good luck.

Assembling the aft section is straight forward. I suggest printing the top halve pieces in white, except for the speed brake which I suggest a darker color. The bottom halves, ruddervators, and the body flap, I suggest the dark grey color and the nozzle you should print in black. The small back surface inserts (connectors) should be black. First assembly is the top forward pieces: mate these two halves together with the required ‘bag’ and insert it on top of the bottom TPS piece with the tab. Next assemble the top back piece halves with their bag and the speed brake. Add the small back surface (connector) inserts. I slightly tapered the six small connector pieces to allow easier insertion. So, be sure to insert the smaller end first. Lastly, you can insert the ruddervators, the nozzle, and the body flap. You will note that you will insert the nozzle, not centered, but in the right half. This is true to the X-37B design. You can now mate the aft section to the wing and PL section. If anyone specifically wants a centered nozzle (original X-37 design) then I will add that as an option.

Finally, we are ready to assemble the forward section. You should print the top piece in white, print the bottom two TPS pieces in dark but not black. Finally, print the nose piece in black. You mate the bottom two TPS halves with the ‘bag’ and the nose and top pieces mate with the provided tabs. Once you assemble the forward section, you can mate the three assemblies. And you have the finished model.

The last step is to print the stand to be able to display your model. The lettering on the stand plate is raised to help with painting or printing in a different color. You can now insert the stand pin into the model, and you are finished. Please publish your make. I would love to see the final product.