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Welcome to the February issue of the DEFCAD newsletter. This month we highlight Professor Parabellum's DIY .410 / 45LC Shot Pistol, which is not only fully modeled, but designed explicitly for home manufacture. Of the professor's many designs, this one may be the most simple and pleasing in appearance. One of the major benefits of using shotgun shells with these sorts of builds is not having to use a rifled barrel.

Following the Shot Pistol, Unseen Killer has provided his MAC-11 PMAC Remix. The MAC remix is Unseen Killer's take on a guncad classic. This is a robust platform that begs to be remodeled.

Our final highlight of the month is Hoffman Tactical's SL-15 V4.8a, which marks the 3rd generation of his 3D printed AR-15 lowers. Designed from the ground up, the SL-15 features an integrated grip, the option for metal front plates, improved strength, better ergonomics, and improved part fitment. Every aspect of the design has been reconsidered and refined.

A brand new license standard made in collaboration with PLA+ Boi and The Gatalog. Forget free software. This is a radical, innovative take on Boomerized licenses. None of the bullshit legalese. Just simple English and the quiet satisfaction that you've definitely, 100%, stopped someone from jacking your intellectual property.

Remember: Free Men Do Sometimes Have to Ask. Comes with activities!

As a first release in what will surely become a recurring segment -- let's call it "The Gatalog Papers"-- the editors of DEFCAD sat down with a concerned guncad community member for a brief, but frank, on-the-record discussion. This interview was recorded at the beginning of February, and subsequent events have borne out the concerns expressed by this couragous whistleblower.

Don't miss this rare, candid look inside the nation's most active and influential 3D-printed gun organization. A Must Read interview.

If you'd like to be next to speak in this series, please email the editors at [email protected].

This week's newsletter is brought to you by the Print Build Shoot 43 from ghostguns.com. The Ghost Guns PBS series has become one of the country's most popular kit offerings since the demise of VanDerStok and the commercial retreat of Polymer80. A new take on public broadcasting.

Pick up your PBS 43 kit today! Only at Ghost Guns.

When busy printing, we'll sometimes run into problems that we've never experienced in previous prints, though we could swear nothing is wrong with our printer. If we’re dissatisfied with the quality of a print, we may want to look first at our layer height. Layer height settings, measured in mere hundredths of a millimeter, afford the most control over the way our part will ultimately "look", and a good rule is to stick to around 0.20mm.

The next setting we’ll want to look at is movement speed, which is divided into infill speed and wall speed. Slowing things down can frequently improve the quality of our print, offering more time for the extruded filament to cool down.

The third thing we can do is consider using a different nozzle size. Typically, you’ll be using a 0.4mm nozzle, but people interested in higher print speeds may opt to go up to 0.6mm or 0.8mm. Inverting that, we can imagine that going for small nozzle sizes (such as 0.3mm or 0.25mm) might increase part fidelity by virtue of being able to print thinner features.

Another experiment in DIY manufacturing has been completed by CNC Kitchen: what if layer lines could be stacked in the same manner as bricks?

This experiment in improving layer adhesion and strength is directly applicable to our work in DIY Defense. Since the interlocking of layer lines is not a standard procedure for slicers, CNC Kitchen had to get creative. He ended up using a propriety slicer to interrupt the layer plane by printing perimeters in a zig-zag, bricklayer pattern.

After running a set of exhaustive tests using his standard designs and metrics, he was able to show a consistent 10% strength improvement. The failure modes also changed significantly across all tests. Overall the video is worth watching, and while the cost of Simplify3D may scare you away, this approach to alternating permiter heights is worth continued investment.