Maker Lamp concrete casting kit

Loving my Maker Lamps, I decided to make a cast concrete base. Giving them a good heft and making them less likely to topple over when tugging on the cord or manipulating with other items in a near vicinity, as well as nice contrast of materials and textures.

Mold is designed for lamp by with 40mm socket hole, for bigger diameters you can easily print a separate bushing with 40mm inside diameter and your desired size on the outside minus 0.1mm for clearance. 

Bill of materials

• 3d printed parts for the mold (plug, bottom, 3x wall segment, optionally 2 parts of mold padding)
• 3d printed body insert. This part will be embedded into concrete mixture and will form all of the basic lamp body features. 
• 3d printed bottom lid. Due to changes to the body geometry, new locking surfaces are need. 
• 6x 19 mm Binder clips. Other sizes or styles of clips will work, but grooves in the mold walls are based around 19 mm size. 
• Two-part casting silicone. Using mold padding, 500g can of silicone was just enough to create the casting, but exact measurement will differ for different brands and formulations.
• Concrete mixture. Depending of specific of the mixture, casting should use about 800g of the concrete. Art concrete mixtures are highly recommended as they are formulated to create smoother surfaces. 
• Original Maker Lamp body. Will be used for creation of silicone mold, process should not damaged part in any way and you can continue to use it as intended. 
• Mixing cups, mixing utensils. 

Printing instructions

All parts of the mold has been printed out of PLA at 0.28mm layer height (or Draft quality). No surfaces in the kit are dimensionally critical. Mold plug uses a layer height modifier in .3mf file to prevent leaks of silicone and concrete into casting cavity, but it is not absolutely needed. Mold plug and Mold walls come pre-supported in .3mf file with bed adhesion aids (Helper disks). It is not critical that parts do not warp, but improved bed adhesion is recommended to avoid print failures. To save on amount of plastic used, using Lightning infill is recommended, with exception of Mold Bottom, which struggled with print artefacts on big flat surface.

Casting

Casting process requires two steps. First the mold parts and original Maker Lamp body is used to created flexible silicone imprint, then mold gets reassembled with new replacement body insert and covered with concrete shell. 

No modifications to existing Maker Lamp body are necessary. You might want to consider using a bit of filler to cover the seams on the print if they look out of place. Silicone and art concrete will capture all of the surface details faithfully, but some correction of the final concrete surface will be possible using a sandpaper. 

Be aware of potencial risks that comes with handling uncured silicone or powdery concrete mix. Observer proper precautions when handling the materials. 

Casting silicone

• Assemble Mold Bottom and Walls using binder clips. Walls and Mold Bottom do not lock together, but should seal tightly enough for viscous silicone not to leak out during the pour. If in doubt, you can either run a bead of hot-glue on the inside of the mold, or tape over the seam.
• Slip Maker Lamp body over the Mold Bottom guide. 
• Insert Mold Plug into lamp body to cover cable routing channel. Make sure that everything is centered. and plug outer ring sits on the lamp body. 
• Mix silicone according to its instructions.
• Pour silicone over the lamp body in single tight stream, avoiding creation of bubbles and let it freely flow into the undercut between the mold bottom and lamp body.
• You can either fill entire mold with silicone, use cutted up old silicone molds to pad out the silicone volume towards the end of the pour, or add mold padding parts after the silicone has been poured to raise its level around lamp body to cover it completely.
• Add weight on top of the Mold Plug to make sure everything stays in correct place during curing.
• Let the silicone completely cure. 
• Demold the lamp body, starting with removing of binder clips and peeling off the mold walls. Follow up with removal of mold plug and mold paddings if they were used. Peel the silicone off the mold bottom and remove the Maker Lamp body out of the silicone.

Casting the concrete

• Assemble Mold Bottom and Walls using binder clips.
• Concrete should demold from the mold with no problems even without use of mold-release agent, but a thin layer of cooking oil can be used as separation layer as replacement to dedicated product. 
• Slip Body Insert over the Mold Bottom guide.
• Add silicon part over the Body insert.
• Secure and align both silicon part and Body Insert using Mold Plug. Make sure that that silicon part grips outside of the plug and that plug's inner ring sits over Body Insert edge. 
• Mix concrete according to its instructions.
• Pour concrete mixture into the gap between inner and outer ring off the Mold Plug. Inside surfaces of the Body Insert are not critical, but take care not to spill too much concrete inside as it is will become more difficult to properly seat light fixtures.
• Pour concrete up to the edge of the Body Insert. Some shrinkage of concrete around the what will become bottom of the lamp is expected and will be correctable in limited amount by sanding. 
• Vibrate mold slightly to dislodge any air bubbles.
• Let the concrete completely cure.
• Demold finished lamp body from the mold.

Lamp Assembly 

Before the assembly, consider giving newly casted part a light sanding and clean to remove any blemishes, tone down the layer lines casted into it and clean all of the debris from the process.

Concrete lamp body can assembled with original Maker Lamp shades and covered with Bottom Lid part once all of the cable management is done.