Human Cell Mini Golf

Here's how a few folks from the Brooklyn hackerspace NYC Resistor created a mini golf hole inspired by a human cell for the annual Figment mini golf course on Governors Island (opens June 3 2016)! The theme of the multi-hole course this year is "mini is the new big," and after proposing our science-themed idea to the open call for submissions, we were selected as as one of the teams to construct a hole for the course. This Instructable follows the process of its construction and is a collaboration between Colleen AF Venable, Guy Dickinson, Chris "Widget" DiMauro, Ryan Micaleff, Ranjit Bhatnagar, and Becky Stern.

Special thanks to all members of NYC Resistor, Figment organizers, and creators of the other holes on the course!

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It had been a while since any of us had been mini golfing, so we headed to Pier 25 to remind ourselves what we liked, what stuff is made from, and chat about our construction plan.

Tools we used at NYC Resistor:

• ShopBot CNC router
• regular wood router with table
• cordless drill driver (aka "screwgun" according to some)
• mitre saw
• band saw
• handheld jigsaw
• handheld orbital sander
• chisel
• mallet
• file
• clamps
• tape measure
• level
• pencils/markers
• laser cutter (optional)

Materials from the home improvement store:

• 8 4x8 sheets of 3/4" plywood
• 10 2x4s (10ft)
• 3 2ft pieces of 4" PVC pipe
• 4" PVC drain assembly
• green outdoor carpet
• other outdoor carpet/door mats
• waterproof wood glue
• exterior paint
• rollers, brushes, paint trays
• plastic dropcloth
• painter's tape
• screws
• 8 lag bolts each with one washer and one nut

After looking at many illustrations and diagrams of human cells, we created vector art in Illustrator to determine the size and shape of the course and its obstacles. For variety, we created one obstacle on the laser cutter (5 layers of scrap acrylic glued up), however the majority of this project was cut by the ShopBot CNC wood router.

There’s no need to use expensive, cabinet-grade plywood that’s perfectly flat and voidless for a mini-golf hole. It’s going to live outside, you’re going to sand and paint it, and it’ll be trod on, kicked, bashed with golf clubs, and otherwise abused for months. Plywood sheathing will do just fine. It does come with some tradeoffs, though: it’s full of voids (gaps between the layers of wood), it’s inconsistent in thickness, and it’s absolutely crammed with glue between layers to make up for the lower quality wood.

Attach it to the spoilboard as flat as you possibly can, and use more screws than you would with high-quality wood. As you cut pieces out of the wood, the wood will likely deform even more as you change the internal stresses. It’s helpful to counteract this by adding more screws.

A quarter-inch down- or up-cut end mill will work just fine. Don’t use anything smaller - the large amount of glue inside the wood will wreak havoc on smaller bits. Design your artwork to avoid any curves that your bit won’t be able to reach.

The voids inside the wood mean it’s possible that a retaining tab will end up missing because there isn’t any wood there to support it. Add extra tabs! Plus, the wood will likely warp as you remove parts of it, so ensure each curve in your design is well supported.

If your plans don’t involve tool changes, consider using the spoilboard as your zero-reference, so that the inconsistency of thickness over each sheet of plywood won’t matter as much: you’ll always be guaranteed to go through the material eventually. Similarly, measure each piece of plywood separately and re-calibrate your toolpaths to suit: There can be as much as a quarter-inch of difference in thickness between individual plywood sheets. If your toolpaths do involve tool-changes and you don’t have access to the spoilboard while the stock material is on there because it covers the whole thing, you’ll be stuck with using the top of the material as the zero reference. This is where trying to keep the material as flat as you can is of critical importance: try and make the material as flat as possible with extra screws (see above) and then take your zero-reference from near where the next cut is going to take place.

Once the material and ShopBot were all set up, time came to cut out vectors! To remove cut pieces, we used a chisel and mallet to cut the tabs holding it in place, and repeated the cutting process for all pieces of the playing field, border, cell organelle obstacles, ramp/tee, and microscope sandwich board.

For safety, we all wore hearing and eye protection and never left the machine unattended.

With so many squiggly blobs, it was hard to keep track of them all-- we marked all the pieces' top sides before taking them off the bed, and still managed to flip some of them upside down later on!

For pieces like the mitochondria, perform pocket cuts before profile ones: The tabs left that hold the workpiece into the stock material will probably break under the stress from the pocket cuts, so do them first while you have more supporting material to work with.

Some of our sheets created floaty pieces, such as the playing field and long edge pieces. We paused the machine and added a few more screws sandwiching the plywood to the base in these cases (again avoiding the router's path).

The ShopBot makes some pretty awkward plywood scrap.

Keep beverages covered and protected from dust! =D

Our obstacles were created using two layers of 3/4" plywood, stacked. Using waterproof wood glue and a whole heck of a lot of clamps, we matched up like pieces and glued them together. After drying overnight, we used a wood router to round over the edges of all the top sides of the pieces. It was helpful to reference the vector art to double check the orientation of the pieces so that the correct side was routed.

The microscope sandwich board edges were routed flat on the floor. Then we put the router into its table to round the edges of the obstacles.

We covered our space in plastic drop cloth, and used a ladder to prop up the microscope pieces, which Colleen expertly painted. The obstacles and backboards were painted solid colors using two coats of exterior paint, and predrilled for attaching to the playing field.

Similar to the obstacles, the edge of the course is a glue-up of ShopBotted plywood, but this time it's three layers of 3/4" plywood at the edge of another layer which is the playing field, and screws were used in addition to glue. We used a file and orbital sander to smooth out the edges where the tabs had been.

The frame supporting the playing field is made from 2x4s, and eight lag bolts are used to secure the four pieces of the "pie" through points in this frame.

These quadrants were designed not only to be cut from standard sized plywood, but also to be small enough to carry and be transported in a freight elevator and van.

The mechanics of how our hole would function was only loosely established during the design process, and many elements of this section came to exist as needed and with little precision. The angle of the ramp was determined by how shallow we could adjust our chop saw, and the piece joining the two microscope boards is just a trapezoid that "seemed good" to us as we were building.

The general idea is that the golfer launches the ball up the ramp, at which point it flies off, hits the backboard, and drops straight down into one of three PVC half-pipes directed at different areas of the flat course.

Turns out our tee was too short to swing a club, consequently, and you'll see that we lengthened the flat platform between taking these photos and installing the pieces.

The tubes connecting the ramp were halved on a band saw.

We loaded our pieces into the elevator, into a van, then into a truck, then out of a truck before assembling it in place. We packed golf balls for playtesting, spare paint for touchups (of course the trucks provided a few dings here and there), the green carpeting, and a bucket of tools.

Onsite during build day was HOT and SUNNY. Prior planning put us in the best possible situation, which was great because the heat made us all delirious. Many breaks for shade, snacks, and sunscreen occurred.

After installing the lag bolts that hold the course together, we flipped it right side up and drilled some DRAIN HOLES-- We didn't think of this at all before the organizers suggested it. So then we drilled three big holes in each corner of the course where we thought water might pool.

We stapled the carpet down at one side, then flattened it over the course and cut it to shape using a utility knife. Then we flipped it open and applied spray adhesive (3M brand, type 90) to both the plywood base and the back of the carpet before affixing it in place (following the instructions on the can).

We waited until last to staple down the carpet around the edges, and hammered the staples down.

There were some tasks we knew had to wait until everything was in place, since the pitch of our outdoor location would greatly affect playability (although we did shim the playing field to make it as level as possible). This includes organelle placement and tube adjustment.

We had a blast test playing the cell, then adjusting the pieces to change how easy/difficult it is to sink the ball.

We had less of a blast trimming the PVC tubes to close up the opening under the ramp (to prevent balls from getting lost in there, another suggestion from the organizers) with a jigsaw.

After we were happy with the placement of the obstacles, we screwed them down to the playing field and painted over the screws.

This was our team's first time making a hole for a mini golf course, and we're sure to learn about its durability over time, since the course will be open all summer 2016 at Governors Island-- come check it out!

Update after two months of use (third photo): Still going strong! No maintenance calls yet, though it is getting dirty and the paint is starting to crack in a few spots from weather. There is notable grass wear near the tee, changing the height of the step up-- something to keep in mind for future designs.