This model of the Transamerica Pyramid was designed and built for Subpar Miniature Golf, for the new location in San Francisco. Images and text are posted here with the owner's permission, come play a few rounds after the opening in April, 2018!
Step 1: Gather the Materials
First we need a sketch, CAD drawing, or 3D model of our building. The model for this project was designed at Subpar Mini Golf, and is very slightly squished from the proportions of the real building to fit the ceiling height where it will be installed. AutoDesk has some downloadable models, and other creatives have uploaded their versions. Or you can create your own!
For this building the area underneath is meant to be a mini golf obstacle, and take more than a few hits from golf balls. For strength and durability I designed the lower portion in steel and the upper pyramid in MDF. Regular wood could have been used, but MDF has a uniform texture and isometric properties (it behaves the same under force in all directions) providing a uniform surface for a later paint job, and a reasonable surface to repair in the case of a wild swing from a patron.
Eye Protection (wrap around glasses)
Ear Protection (Muffs over 30 decibels or ear plugs as you like)
steel toed or safety boots
Welding face shield, treat yourself to auto-darkening ;)
Follow general shop good behavior: no loose clothing and roll up long sleeves when using any tool that spins. Never wear gloves with tools that spin. Always wear gloves when welding and handling metal on or near the welding table (hot metal can look cold!) Tie long hair back.
Respirator and Dust Mask
For the top:
2 sheets of 3/4" or 5/8" MDF, size 4x8'
Pneumatic Nail Gun and Compressor (with nails)
Wood Glue (get a gallon jug!)
Bondo (to fill and flush hardware holes)
Wood screws over 1" long
Drill and Driver to go with your screws
Router (table or handheld)
Recommend: True Track for clean, long cuts with the circular saw
For the Steel Base:
.125x.5" Flat, 48'
1" Angle, 16'
.5" square tube, 10'
.5" angle, 10'
Welding wire (flux core or MIG + Gas)
Wire brushes (for cleaning and preparing welds)
Pliers and snips
Angle grinder and cut off wheel, flap disc, grinding wheel
and/or Chop Saw with an abrasive disc for metal
Step 2: Make a Cut List
I'm working from the base up on this, and I want that base strong and solid.
I opened the model in Fusion 360 and took measurements for each of the angles and straights, but since we're on a budget for time and resources, getting it visually correct was more important than mathematically perfect. The base pieces reaching vertically to the ground are 9" to allow golfers a chance to see where their ball may have gone.
The overlapping geometric middle, 20 pyramids around the outside (which would be poured concrete on the real building), are flat to .5" stock to save weight and cost. They will meet at an angle on the flats to give the illusion of volume from a distance, and are overall 7" tall.
Top and bottom rail are 1" angle, top turned up to hold the MDF later, bottom turned up to hold all those nice angles. The interior rails are .5" angle.
Top rail of Angle is cut to four 24" sections with a 45 degree miter cut to join the corners
Bottom rail of Angle is cut to four 30" sections with a 45 degree miter on the ends
We need 7.15" flats, 4 sides to each mini pyramid, and 20 pyramids
Step 3: Cut Your Metal
I always cut large pieces first, that way if there's a mistake you can cut a large piece into a smaller one. Although we are welding and there is some flexibility, it's an unpleasant use of time to add back on to material you've cut down.
I start by cutting 4 pieces of 1" angle to 30" each,
and then 4 pieces of 1" angle cut to 24" each
A good tool for cutting down many pieces that are all the same size is a chop saw with an abrasive disc for metal, and a fixture to set the desired length so you can cut the pieces one right after the other without much downtime. In a pinch, if say the chop saw is down for maintenance, putting a clean cutoff disc on your angle grinder will work just fine. You absolutely must wear eye protection with any abrasive tool! Consider a face shield as well, particularly when sanding, grinding, or otherwise de-burring the ends and edges. And leave that guard on your grinder!
Be sure to clamp or secure your material to prevent injury and/or bad cuts.
To aid the illusion of volume, I'm using that .5" angle on the pyramids that make up the corner pieces.
With that in mind we need 16 pyramids of flats, 4 sides each, and 4 pyramids of angle, also four sides.
That gives us 64 pieces of 7.15" flat steel
and 16 pieces of 7.15" angle.
For the rails, you'll need to cut a miter into one edge at 45 degrees. This can also be done with your cutoff disc and a steady hand. An easy way to see how the miter lines up is to assemble the rail pieces into position, then mark the angle from the corner where they overlap.
Step 4: Make a Lil' Fixture
The .5" angle pieces meet best if you miter a 30 degree angle onto each side of one end. I wanted a fixture to hold the pieces in position while welding, but the shop was just being set up and supplies were limited. My prototype fixture was drawn on craft paper and assembled from scrap wood. It did an OK job holding the pieces up in position, but was not suitable for extended use on a welding table. I took those measurements and made another fixture from scrap flat steel that I could clamp down to my steel slab and use for welding.
I made another small fixture for holding the .5" flats upright. These pieces were also supported by welding magnets.
Time to make ALL the pyramids! The nice part about getting this whole set done at the same time is that I could check my new pyramids against the old and make sure the variations were not large or noticeable. If we had more time I would have liked a more substantial fixture that would hold these pieces in precise position, but I'm happy with the fast results.
Step 5: Assembling the Rails, Adding the Corners
The spacing between the corners was set, making it a good place to start the overall assembly.
Check the level of the four corner pyramids (made of .5" angle) and weld the top rail on first while they have a nice even footprint on a nice even table.
The 1" Angle has a wall thickness of .125" which is something to keep in mind with adding the bottom rail: It's a good idea to have a .125" shim or spacer under all of the pyramids' feet to maintain the level. This can be achieved with off-cuts of angle or scrap of the correct thickness.
Step 6: Add in the Rest of the Pyramids
I laid out the pyramids against the rails and decided on a spacing that was visually reasonable, this may vary by scale. Using the same shims employed to support the corner pyramids, I welded these from the bottom up, occasionally adding a little extra weld material to the tops when they came in just a bit low. Given that they would be under a feature near the floor, I don't expect the average patron to ever see a little extra glob of steel in there ;) however if you're building a model where this feature is at chest or eye height, consider spending more time getting the measurements just right.
There were a few locations where the overlap between the corner pyramids and the flats was a bit awkward. I simply cut off any pieces that were protruding in a way visually disrupted their surroundings.
Next, the .5" angle for the interior rails is cut to size and welded in place.
Step 7: Add the Base Feet
Me: "This next part will be easy, it's all right angles now."
Also me: "I need an aluminum angle and every clamp in the shop..."
As you can see from my sophisticated napkin drawing( improvise when you need to) the spacing for the base feet was decided upon by two factors: it needed to be strong enough to hold up the whole structure on .5" square tube, but not so dense you couldn't successfully get your golf ball through.
This was one of the few times I used the angle grinder to take down welds; I wanted each of these to meet a flat surface for stability, so the bottom rail needed to be smooth.
The pieces at the four outside corner are slightly longer than the others, by 1", so that they can be sunk deeper into the floor.
Step 8: Time to Work With MDF, Make a Cut List!
Going back to the model, and knowing that the sheets of MDF were too short to simply cut each side entirely, I chose what seemed a logical point for the break: the bottom of protruding architectural detail.
Using these measurements I marked the MDF with a nice, sharp pencil. Now it's time to cut!
Step 9: Cut Your MDF Pyramid Sides
Have I ever told you how much I love the True Track for a circular saw? Oof. Friends, I love this tool.
I've been absolutely spoiled by access to a ShopBot CNC router (miss you bae) but this had to be done by hand. I certainly don't trust myself to make a cut that long and that straight without some mechanical assistance. Each piece also needs a miter edge of 45 degrees. Using the True Track and a circular saw with a matching guide, you can set your cut to miter as you go or make your cuts clean and straight and take your pieces to a router table.
We didn't have a proper router table per se, but we had a handheld router and... a table. Easy enough to bolt the router to the bottom of the table and use as normal.
Remember your shop safety! Tie back all hair and loose clothing, nothing hanging down, NO GLOVES, and use eye and ear protection.
Step 10: Check Your Fit
My lovely assistant Mike *cough (boss) cough* was kind enough to lend a hand aligning the mitered pieces for a test fit.
In order to set this up as a four sided object from eight pieces, I fixed the top and bottom pairs together using a 1x2 cut to 3' on each. This was glued on the inside and nailed with the pneumatic nail gun on the outside, and left overnight to set up.
Step 11: Fix the Edges
To get this all cleanly and properly aligned, the upper MDF was placed in the steel frame for assembly. It was here that we began to see the real downfall of MDF: it had swollen over a rainy weekend and no longer fit just right.
No sense in starting over; I simply trimmed the corners of the bottom of the MDF and slid the four bottom sections in place.
From here I needed a hand holding the pieces securely in place as I glue and nailed the entire length of each corner.
Step 12: Add Extra Stability
In what might be considered a little overbuilding, I crawled inside the pyramid and placed 4" long, 1x1" cuts of lumber along each seam, glued on the inside and screwed down from the outside.
Countersunk screw holes were filled with Bondo for a smooth finish.
Use a respirator with Bondo and/or be sure to use in a well-ventilated area.
Step 13: Make the Details!
Back to the model or drawing for proportional measurements!
These pieces were created with a template on the 5/8" MDF cut out with a jigsaw and sanded down. Aligned and glued overnight, it was a relatively quick process. Irregularities were smoothed over with Bondo and sanded.
Step 14: Fixing the Feature
With the main pyramid on its side, I measured top down, bottom up, and across the middle to get these two pieces aligned just right. The seam made for a natural guide.
These were glued generously and fixed in place with the pneumatic nail gun, then the seam and nail dents filled with--you guessed it--more Bondo.
And that's it! It's ready for paint!