A battleship-style drinking game board is one of the more entertaining weekend builds a woodworker can take on. The finished piece is a briefcase that opens flat into two playing fields, each drilled with a grid of holes that hold tiny plastic cups. Two players set up their cups, call coordinates at each other, and remove a cup every time a shot lands. The build teaches skills that carry over to real furniture: laying out a grid, cutting sheet goods, drilling clean holes, and installing hardware. This article walks through the case design, materials, grid math, and finishing so the board comes out straight, sturdy, and ready for the next game night. The whole project fits in a single sheet of plywood, and the only specialty tool is a hole saw.
How the Game Board Works
The board borrows the coordinate system from the classic naval guessing game. Each half of the case is a playing field, and the grid gives every cup a callable location. The cups sit in drilled holes so they stay put when the board is carried or bumped, and the game ends when one player has cleared the other side.
Game Rules in Brief
- Each player arranges a set of cups anywhere on their 10 by 10 grid
- Players take turns calling coordinates, one column and one row per turn
- A hit means the cup at that square is removed and its contents are consumed
- The first player to clear the opponent’s cups wins the round
Why a Hinged Case
The case format does three jobs at once. Closed, it protects the cups and carries like a briefcase. Open, the two halves become the playing fields, one per player. The hinges let the halves lie flat, and the latches keep the board closed between games. A simple wooden tray or foam liner inside gives the loose cups a home during transport. Choose hinges with enough throw to let the halves sit flat, and position them so the screw heads do not collide when the case closes.
Choosing Materials for the Case
The original build keeps the material list short: 3/4-inch pine plywood for the panels, 1×4 pine boards for the frame, and a 1-1/4-inch pine dowel for the feet or handle. The plywood provides a stable surface for the grid, while the pine frame stiffens the edges so the case does not flex when it is carried by one corner. A dark stain and a protective finish give the board a bar-quality look, and the hardware is standard briefcase stock.
Plywood Grade and Thickness
Sanded pine plywood in 3/4-inch thickness is the right starting point. It is strong enough to hold the cups without sagging, and the smooth face takes stain evenly. Cabinet-grade plywood with a birch face costs more but delivers a cleaner edge for the grid. Avoid construction sheathing, which has voids that show up at the drill press. Check the sheet for warpage before cutting, because a twisted panel makes a twisted case. Store the sheet flat for a few days before cutting if it has been leaning against a wall, because plywood that has taken a set will fight the case hinges forever.
Hardware and Finish
The supply list below covers a two-player board with room to spare. Buy the cups before you drill so the hole size is set by a real measurement. Cup diameters vary between brands even when the capacity is the same, and a board drilled for the wrong cup is a board that needs re-drilling.
| Item | Typical size | Purpose |
|---|---|---|
| Pine plywood | 3/4 in | Case panels and grid surface |
| Pine boards | 1×4 | Frame rails and stiffening |
| Pine dowel | 1-1/4 in diameter | Feet or handle stock |
| Briefcase latches | 2 per case | Keep the case closed |
| Handles | 1 per case | Carrying |
| Mini plastic cups | 2 oz | Game pieces |
| Black stain and finish | as needed | Color and protection |
Cutting the Panels and Building the Case
The case is two identical panels joined by hinges. Each panel gets a 1×4 frame around its edges, which builds up the thickness so the drilled cups sit below the rim instead of poking through. Cut both panels to the same size, then frame them, hinge them, and add the latches and handle. A 24-inch square per half is a comfortable size for a 10 by 10 grid and still fits on a table.
Cut List and Panel Prep
Cut the panels oversize by a half inch, then trim them to final size after the glue dries. That sequence corrects any drift from the saw. The frame pieces are cut from 1×4 stock, and the corners can be mitered for a clean look or butted for speed. A track saw or a circular saw with a straightedge keeps the long cuts square, and a drill/driver with a countersink bit handles the frame screws. Clamps are worth borrowing if you do not own them, because the frame joints need pressure while the glue sets.
Assembling the Two Halves
- Cut the plywood panels to final size, keeping the corners square
- Miter or butt the 1×4 frame pieces and attach them with glue and screws
- Lay the panels face down and mark the hinge locations on the mating edges
- Install the hinges so the case opens flat with no gap between the halves
- Add the latches and the handle before moving on to finishing
Laying Out the Grid and Drilling the Cups
The grid is the heart of the build, and the math is straightforward. Decide the panel size and the margin, then divide the remaining space into 10 equal columns and 10 equal rows. Mark every intersection, drill a pilot hole at each one, and open the holes up with a hole saw or Forstner bit sized to the cups.
Grid Spacing Math
Center-to-center spacing equals the usable width divided by 10. A 24-inch panel with a 1.5-inch margin all around leaves 21 inches of usable space, which works out to 2.1 inches between holes. That spacing leaves enough plywood between holes to keep the grid rigid. The table below shows the numbers for three common panel sizes.
| Panel size | Margin | Usable grid area | Center-to-center spacing |
|---|---|---|---|
| 24 x 24 in | 1.5 in | 21 x 21 in | 2.1 in |
| 30 x 30 in | 2.0 in | 26 x 26 in | 2.6 in |
| 36 x 36 in | 2.5 in | 31 x 31 in | 3.1 in |
Mark from the center of the panel outward instead of from one edge, so any small error lands in the margin rather than accumulating across the grid.
Choosing the Right Hole Size
Measure the rim diameter of the cups you plan to use, then add about 1/8 inch for the hole. A hole that is too tight makes the cups stick when you try to pull them out, and a hole that is too loose lets them wobble or fall through. Test one cup in a scrap piece before drilling the whole grid, and keep a second hole saw on hand in case the first one wanders. Forstner bits leave the cleanest hole in plywood, while a hole saw works faster and tends to tear the face veneer on the exit side. Clamp a scrap board underneath the panel and drill through both, which eliminates blowout.
- Print or draw a 10 by 10 grid template at full scale
- Tape it to the panel and transfer every intersection with an awl
- Drill a small pilot hole at each mark, then cut the holes with a hole saw or Forstner bit
- Sand the inside of every hole and test-fit the cups across the whole grid
Finishing, Hardware, and Custom Details
Sand everything down to 220 grit before finishing. A black stain gives the board a barroom look and hides spills, and a clear topcoat protects the surface from the condensation that collects on cold cups. Apply the finish to the inside faces of the case as well as the outside, because drinks will find every surface eventually. Let the finish cure fully before installing the hardware, then screw on the latches, handle, and feet.
Staining and Sealing
Wipe-on stain is forgiving on pine, which tends to blotch with brushed stain. Apply a thin coat, wipe off the excess, and let it dry before the second coat. Follow with two or three coats of polyurethane or a satin oil finish. Let each coat dry according to the can before sanding lightly with 320 grit between coats. If the board will live outside or in a damp garage, add a coat of exterior-grade sealer.
Custom Details and Optional Upgrades
- Paint or stencil letters and numbers along the grid edges so coordinates are easy to call
- Add a chalkboard or dry-erase strip to one frame rail for scorekeeping
- Install rubber feet on the outside corners so the open case does not slide on a table
- Build a foam-lined tray inside the case to hold the cups and any spare pieces
Measure twice on the grid and the rest of the build goes quickly. A straight, level case with a clean grid and hardware that clicks shut will survive years of game nights, and the layout and drilling skills transfer directly to shelving, cabinetry, and any other project that needs a precise hole pattern.