3D print this, pour in plaster and you're ready to start slip casting! I recommend doing the small size first. My previous work on this mold assumed a smaller 3D printer (making it necessary to print flanged PLA mold sections that clip together). But larger 3D printers are now common (e.g. Creality K1, Bambu X1/P1, Prusa Core1). This makes the CAD work much easier. This CAD drawing is parametric for height, diameter of the body, the plaster thickness and neck height (for the full bottle set body=160mm, neck=96). Neck vertices are proportional to its height, so the shape resizes well. This uses my standard clips and embeds. The top and bottom are filleted and chamfered to permit the longest possible mold to fit on the print bed diagonally. This is for prototyping and making a few molds (since it prints with artifacts (which will appear as wood grain), later I will create a hybrid that employs a plaster model with a 3D printed base plate. The PLA mold prints quickly, it has a hollow back side, permiting easier removal with a heat gun. The bottom inside is chamfered, which helps assure that the thin side wall is well connected to the base. This mold has no spare (on purpose), it employs a pour spout, making the mold shorter it producing a better lip.

Need a stoneware slip casting recipe? A glaze recipe? We can help you go full DIY. A black burning clay body with amber and honey glazes works best to get the deep beer bottle glass color.

Glue one of these on top of your slip casting mold (using slip) and enjoy the many benefits. These are intended for people who make their own molds using the 3D printing techniques taught on this website. Among the advantages are the following:
-Less mess.
-Smaller, simpler molds (they don't need a spare).
-Overhung lips, more precise lips.
-Visible indication of casting progress.

This is the L3954B engobe. 15% Mason 6600 black body stain has been added (instead of the normal 10% Zircopax used for white). Of course, a cover glaze is needed for a functional surface. We put a lot of development work into producing a recipe fits this body, M340. It works even when thickly applied because it has the same fired maturity as the body. Lots of information is available on using L3954B (including mixing and adjustment instructions). Engobes are tricky to use, follow the links below to learn more. L3954B is designed to work on regular Plainsman M340 (this piece), M390 and Coffee Clay. Most important we document how to adjust its maturity, and thus firing shrinkage, to fine tune fit if needed. These bodies dry better than porcelains and are much less expensive, so coating them with an engobe to get a surface like this makes a lot of sense. Ed Phillipson discovered this 80 years ago, enabling selling ware made from these clays as white hotel ware.

These brass/plaster pyramids embed into plaster to provide a threaded hole that M3 bolts can screw into. That enables attaching 3D printed elements to plaster elements when making hybrid molds. Narrow inserts permit placement in cramped spaces and nearer edges.

These are made possible using M3 brass knurled nuts and M3 bolts that can be purchased on Amazon. The brass nuts can be pressed in using a soldering iron. The pyramid-shaped 3D-printed anchors are 13mm high, they will accommodate 12mm, or less, inserts (the longest ones in the kits shown here bottom left). The holes are 4.4mm dia at the top and taper inward at -2 degrees. Of course, you can adjust sizes and angles as needed for your application.

These two unglazed pieces are made from the same clay, M340. They are fired at the same temperature. But the one on the right has 1% talc added. Greying of the color is a characteristic visual change as this clay body transitions into the vitreous state we target. That transition happens over a narrow temperature range. Because the raw materials naturally vary in the temperature at which they vitrify, we have to tune the recipe so that the transition happens from cone 5 to cone 6. It is accompanied by a drop in porosity of 2% or more (according to our SHAB test). Talc acts as a catalyst for this change; in this case, only 1% is needed. By itself, talc is refractory. Yet it acts as a flux here! The fact that it can effect this big of a change with only 1% is amazing. Interestingly, this phenomenon only occurs with tiny talc additions.

The mold on the right is PLA filament. Printed at 0.8mm thickness, it only weighs 38g yet is very strong. It removes easily from the plaster with a heat gun. The TPU flexible mold weighs 62g (the walls are 1.6mm thick) but it will need a PLA shell to hold the walls vertical (or far thicker walls). It took four attempts to print this. The surface quality is not nearly as good, especially on the top layers. Printing is much slower.

PLA is a bioplastic, made from renewables. It can potentially be composted. PLA is the most common type of filament used in FDM 3D printing. It has a low melting point, which eases printing and improves interlayer adhesion (but heat resistance of printed products is poor).

Regarding TPU, here is some advice from a follower (who uses a Prusa printer and gets better results than us): "The secret to printing with TPU is constant speed while printing. Under Print Settings, go to Speed. Set them all to 20 mm/s. Ironing will be greyed out unless you have it on. Then, in the next section, Dynamic Overhang Speed, set everything to 20 mm/s. Under Modifiers set First Layer Speed to 20 mm/s. Then under Auto Speed (Advanced), set Max Print Speed to 20 mm/s. This will prevent almost all webbing and other print issues. Some people also suggest reducing the Z-Axis Nozzle Retraction, but I have not found a need to do that."

Consider the advantages of making your own clay bodies using a propeller mixer and plaster table.
-Independence: You control product availability, quality and consistency.
-Flexibility: You control the recipe (with our help if needed). Fine-tune and adjust it over time to fit your needs and compensate for variations in material properties and supply.
-Special-purpose clay bodies are possible, ones that ceramic suppliers do not or cannot make.
-The slurry up process achieves better mixing and deairing than any pugmill. No aging needed.
-A mixer and plaster table are useful for so many other things in a pottery studio.
-Achieving the right stiffness is an integral part of the process.
-Recycling scrap, by slaking, fits the process.
-Local native clays: Slurries enable the use of a magnet to remove iron, a sieve to remove particulates and a settling process to remove soluble salts.
-Cleanup is easy so many kinds of clay can be made without cross contamination.
-It is rewarding - you will own the whole process, the bragging rights alone make it worthwhile for me!

This is version 10 of my Medalta ball pitcher case mold. I am still determined that a standard 3D printer with PLA filament brings complicated molds within reach of almost any potter or hobbyist willing to learn 3D design. The project has evolved to become hybrid, using both plaster and 3D prints in the final mold. Two views of the PLA prints needed to pour a plaster half-model are shown at the top.
-Plaster is poured into A.
-I attach threaded anchors to the underside of the baseplate C (using bolts through the small inner holes), they hold the plate firmly in place on the plaster half-model.
-B is a spacer, it is clamped to the underside of C (and aligned using bushings in the holes), it is only used during the model pour.
-Bottom: A is on a perfectly flat and level surface. It was filled with plaster just to the rim and then the baseplate was placed on top of it (the spacer acting to correctly position it). More plaster was added and a few minutes after this it was scraped off flush.
After hardening the spacer can be removed, the mold peeled off using a heat gun, and the plaster surface finished and soaped. The 3D render also shows one of the side rails, D. It holds in place by a flange that wraps under and locks into the holes (the last version used magnets; this approach has several advantages over that).

The 3D design of this handle mold was challenging because of the lack of a defining edge to guide cutting it, at leather hard stage, to accurately fit against the body of the bellied shape (a Medalta ball pitcher).
Center: I solved that problem by creating 2mm pipe along the path defined by the join between the handle and the spares.
Upper left: It has been 3D printed using PLA filament. The walls are only 0.8mm thick so printing is fast. The low profile means there is no bulging from the weight of the plaster. The clips and embeds are in place, ready for the plaster.
Lower left: The plaster cast mold halves (with natches and spacers glued into the embeds). I used a heat gun to remove the PLA prints cleanly (to preserve crisp corners).
Right: The halves fit together perfectly.

A kaolin shipment just came in. "UnReady Freddie" is panicking. He thinks he remembers that products made with the last shipment were lacking plasticity and the fired color was off. He is going to have to come up with different lame excuses for complaining customers this time.

"Ready Freddie" has Insight-Live and has collected years of data on incoming shipments in one searchable place. He knows what to check on each and has fired bars, in-mix tests, particle size checks, data sheets, lots of pictures, notes, etc. He also has traceability - he knows what material batch went into what product. He works with production to do material lot tracking and with purchasing to keep suppliers aware he is testing. Because Ready Freddie knows how materials vary he can compensate recipes and processes so customers see a consistent product.

UnReady Freddie has a few spreadsheets somewhere. But he is busy with other things. Who do you want in charge of product consistency (and company reputation)? Here is what to do next: Have your technician study the page "Testing a New Load of EP Kaolin" (link below). You will be hearing from him/her soon.