In the world of design, "looks-like" models are really important to demonstrate your final design intent. Since you're trying to make something that looks like your final product (as if it were in production), you'd ideally make this prototype out of your chosen materials. If you're like me, you sometimes don't have time/energy/money to stay true to material in your final prototype. The good news is that with a little bit of effort and a lot of spray paint, you can make very cheap or easily accessible materials look like other less common materials.
I had a studio project last year where I designed a planter to help older adults overcome depression as a barrier to aging in place. We were challenged to make a life-sized looks-like model, and I didn't have weeks to create a slip-mold and fire ceramics to achieve my final design intent. I decided to make my planter model out of MDF or medium density fiberboard, a commonly available and inexpensive wood substitute. My model got a lot of positive attention, and it genuinely convinced many of my friends that it was a ceramic piece, despite the fact that I made the model entirely by hand (except the fern). My friends keep asking me about it, so I figured I'd share my secrets.
- 1/4" thick MDF
- disposable rubber gloves
- masking tape or electrical tape
- white primer
- Thick-Clear Glaze spray paint
- Disk Sander
Step 1: Ideate & Design.
I found form inspiration from 12-sided dice, as geometric patterns are big these days in home furnishing. (Think Williams-Sonoma and West Elm.) I iterated on the basic shape with tiny laser cut models until I arrived at the final form, most closely approximated by the foamcore mockup in the last picture.
The "ceramic" portion of my final design was based off of a regular dodecahedron, containing 4 pentagons and 3 trapezoids. The remaining sides of the dodecahedron were either empty or represented by a brazed brass piece. (I will not be covering the brazing in this tutorial. The base was made in a similar method but with veneer instead of paint over it.)
Step 2: Do Some Math.
A regular dodecahedron has 12 sides, which are each regular pentagons. The angle between these sides is 116.5 degrees. Regular pentagons have identical side lengths, and 108 degrees between each side. (Source: Wikipedia) The pentagons for my build were 3.5" per side, but you can make them whatever you like.
The one thing that's completely inflexible is what I call the critical angle, which I calculated out for y'all.
- Each edge on the dodecahedron is the intersection of two planes.
- Assuming that each plane contributes an even amount of material, you can divide the 116.5 degree dihedral angle by 2, which gives 58.25 degrees per side.
- Assuming that your bandsaw is set to cut square, the edge of each material is set to contribute 90 degrees.
- Taking the difference of 90 degrees and 58.25 degrees, you are left with 31.75 degrees.
The critical angle is ~32 degrees, which will be important in a few steps.
Step 3: Cut Out MDF Pieces.
The most important part of making a regular dodecahedron is making sure that all of the sides are identically sized, and the easiest way to do that is by making a template. I made a pentagon template by drawing a pentagon in Inkscape, and cutting it out of random scrap cardboard on the laser cutter. I also made a trapezoid template in the same way. (If you don't happen to have a laser cutter handy, you can spray adhesive to glue a paper template onto your MDF.)
Once you've transferred the patterns for 4 pentagons and 3 trapezoids of the appropriate size, take the 1/4" MDF to the bandsaw and free hand the shapes out of your material.
Step 4: Sand Down MDF Edges to Fit.
Recall the critical angle of ~32 degrees, and angle the table on your disk sander down by that much. Sand the correct sides down on each of your pieces of MDF by evenly applying pressure to the piece as the soft, soft MDF grinds away. Stop applying pressure when you can see the top edge of the MDF being sanded down by the wheel.
For 2 of the pentagons, you should sand down each edge (all on the same face). These will be the top and bottom pieces.
For the other 2 pentagons, sand down 3 consecutive edges, leaving the other edges unaltered.
For the 3 trapezoids, sand down the three edges with the shortest length. Leave the longest edge untouched.
Step 5: Glue Pieces Together.
As you can imagine, gluing the pieces together was no picnic. I used a quick setting epoxy, electrical tape, and a whole lot of patience. The biggest challenge for me was to get the first two sides aligned and glued together.
I used electrical tape as my fixture for gluing. If you apply mixed epoxy to the two edges you want to glue together, and then reinforce/attach them via electrical tape, you can lean the pieces that are curing against a third piece to keep the angle consistent and to provide a more stable configuration. After the first edge cures, you can begin to add one piece at a time, gluing up the 4 interfacing edges of the work pieces (to create 2 edges per addition.)
Step 6: Fill Gaps With Spackle.
Even if you successfully sand down everything to the correct angles, I can guarantee that there will be some gaps, due to the sketchy gluing rig. The good news is that since this is a mockup that serves no real purpose, spackle is an excellent way to patch up those cracks.
Just put on some rubber gloves, and then smear/prod spackle into any gaps and cracks in between your MDF panels. Let the spackle dry.
Step 7: Round Out MDF Edges to Create a Ceramic Details.
The thing about ceramics is that it is nearly impossible for them to retain sharp geometric details, so there are virtually no slip cast ceramic pieces with harsh edges. Since half of making a good model is paying attention to the details, it's worthwhile and time effective to round out the interior and exterior edges of the form.
Because spackle and MDF are both soft, I was able to run an 80 grit sandpaper over and around all of the edges of the mockup to effectively create a 1/8" fillet on the bowl edges. I fully rounded over the exterior angles of the bowl.
Step 8: Paint It and "glaze" It.
Take your model to a well ventilated area, and lightly spray a coats white spray primer over the surface of the model. Wait for each coat to dry before spraying a new one on. (Note that dry times changed based on temperature conditions.) Because MDF is essentially sawdust and woodglue, it can absorb a lot of moisture. Keep that in mind when you are applying your base coat(s) of white paint. Even doing clean, light, and consistent layers of painting from a proper distance, I ended up using nearly a whole can of white spray primer.
After you are satisfied with the coverage of your model, and you can no longer see any of the original MDF texture underneath your paint, you can start applying the Thick "glaze" spray paint. Krylon's website has mediocre reviews for the product, but I found it quite easy to use. The trick for me was to treat it like a normal spray paint, by doing quick, ultra-light coats. To get that glassy sort of glazed finish, I still had to do around three coats of the paint (with adequate time between each coat).
Believe it or not, after I let the last coat dry, I had arrived at my final finish, which looks exactly like ceramic.