No Star Fleet mission is complete without a trusty tricorder. You can build this prop out of inexpensive wood and cardboard, and various things lying around the house. It helps if you have an iphone lying around the house.
Step 1: Caveats
The tricorder doesn't really work. Well, it sends email, browses the web, plays movies and music, but that's it.
It's too big: you can't fit an iphone into a standard ST:TOS tricorder. So we have to be a bit creative with the dimensions. Or maybe you could use an ipod nano.
The screen is incorrect: It's a wide touchscreen with only a single knob, vs a tiny 4:3 aspect ratio with 3 control knobs.
Step 2: Getting Started
I found great reference photos on tk560.com and startrekpropauthority.blogspot.com, with more information on the star trek wiki memory-alpha.org. tk560.com has a set of templates that I used as a starting point (somewhat confusingly under the HOW TO guides for star wars props). You can find various Star Trek sound effects floating around as well. The basic tricorder is about 7 1/8 x 2 1/8 x 5 1/4. Mine is roughly 8 3/4 x 3 1/2 x 7.
Step 1 was to try to mimic the medical display. I wrote an animated presentation in Apple Keynote, saved it as a quicktime, and used itunes to convert it to iphone format. I think the iWork '09 version of Keynote can't export to quicktime, so I hope you kept a copy of the old version. Also, iMovie can't edit quicktime, but it can import the file after it's converted to iphone format, so there was a bit of fiddling here. I did some minor editing and added some scanner sound effects and tested it out. Note that this movie isn't an exact replica of the medical scanner, but it's pretty close.
Step 3: Building a Cardboard Box
So now we have a movie to simulate the medical scanner display. All we need is a tricorder. First, we will build a 3 sided corrugated cardboard box to the precise external dimensions of the iphone. Next, we build a small wooden box to hold the cardboard box (the "head" of the tricorder). Finally, we build a large wooden box to hold the small box (the "body" of the tricorder). So rather than state the measurements up front, you need to derive the measurements from the prior stage, ie the cardboard box must fit the phone, the small wood box must hold the cardboard box, and the large box must hold the small one. And the external dimensions of your phone may vary a bit, depending on whether you have it in a protective case or not.
The cardboard box has a cutout for the screen and speaker, plus a 1/8 inch hole over the "home" button. We'll rig up a tiny piece of dowel rod later to let us press the "home" button to activate the phone once it is encased. The width of the box is exact, but the length is slightly longer than the phone -- I used some additional cardboard shims to wedge the phone in place. Be careful here -- don't destroy your phone.
Step 4: Building the "head"
The top, bottom, middle and sides of the tricorder are made of 1x4 pine (which is really 3/4 x 3.5 inches). The sides of the head are just some scraps of 1/4 poplar. My cardboard is about 1/4 inch which gives me the magic dimensions: 3.5 inches minus the two poplar sides, minus two cardboard sides = 3.5 - (2 x 1/4) - (2 x 1/4) = 3.5 - (1/2 + 1/2) = 2.5, which is the width of the iphone. (Mine actually works out to 2 5/8, which matches the case for my phone).
Cut a piece of pine of the same length as your cardboard box (maybe a hair longer) -- about 5 inches. This is the top lid. The top lid of the tricorder has a semi-circular profile. I just traced an arc on the both sides, then used a drawknife to carve it out. You could use saws, rasps or sanders. Don't bother refining the shape too much -- you will complete the sanding in a couple steps. The easiest way to do this is to screw a piece of scrap to the underside of the lid, and clamp the scrap in a vise, so you have unobstructed access to the top.
Next cut some sides out of the 1/4 poplar, about 3 inches high. Drill and countersink two 3/4 brass screws on both sides -- the distance from the bottom of the side to the bottom of the lid is about 1.75 inches. Trace the profile of the lid on each side. Remove the sides, then cut out the profile just proud of the line. Screw the sides back on, and sand the combined assembly so the lid and sides are smooth. I labeled the sides and the lid with an "A" side and a "B" side since they are now precisely matched.
Step 5: Build the Sides
Cut two 9 inch pieces of the 1x4 pine. Label an "A" side and "B" side. Unscrew the 1/4 poplar pieces from the lid and use them to trace a matching profile on the side pieces. I screwed the pieces in place and used them as an edge guide for my router, but you can just cut the profile with a saw and do some detail sanding to match it up.
Step 6: Hinge Pins
A "real" tricorder is hinged in the rear, but my model has a sliding hinge in the center. Each side has a 1/4 dowel pin about 3/4 inch from the base, and a matching slot is cut in each side. This design gives us a way to access the screws that hold the lid in place after the tricorder is assembled -- just slide the entire head all the way up. Also, it's easier to build a symmetric head -- otherwise you need a long front edge and a short back edge for clearance. The best thing to do is build some paper templates and experiment with hinge position, and make sure that you have sufficient clearance to rotate the head and unobstructed access to both sets of screws.
Drill a hole for the dowel pin, and press-fit 1 inch long sections of 1/4 dowel -- DON'T GLUE IT! The dowel should be tight, but you should be able to remove it with your fingers. It only needs to stick out about 1/4 inch from each side, but the extra length on the inside gives you something to grab so you can retract the pin and remove the head temporarily.
Route or carve a 1/4 inch slot about 1/4 inch deep on each side from the base of the head to just shy of the peak. Test each side with the hinge pin and make sure it slides smoothly.
Step 7: Add Front and Back to the Head
When the head is finished, the cardboard box is glued to the sides, and the lid is held in place with 4 screws. So we need to cut the front and back pieces. With the sides screwed in place, trace a line where they meet the lid. Remove the sides and trim 1/4 inch off each side up to the lid line. Screw them back in place, then cut a front and back piece to the right dimensions -- mine are about 5.5 x 1.75 inches. Don't glue yet! Screw the sides back to the lid, and dry fit the wooden sides with the interior cardboard box and the phone inside. If everything works, then you can glue the sides on. I sandwiched some wax paper between the lid and the sides so I could glue the sides together without gluing the lid in place.
Step 8: Finish the Sides
The tricorder sides have some interesting faceting and tapering, which was short work with the drawknife. Or long work with a sander. There is also a tapered slot near the top where the carrying strap attaches. I did some routing, carving, and sanding to achieve this shape. Be careful not to go too deep, since the hinge slot is on the other side.
Step 9: Cutting the Middle and Bottom
With the head and sides complete, we need to cut a middle and bottom piece to assemble the body. The middle and bottom need to be slightly longer than the length of the head -- about 1/8 inch. Cut two identical pieces out of the 3/4 pine. The front and back plates of the tricorder are just a couple of pieces of 1/4 inch cardboard, so we need to reduce the thickness a bit. The bottom plate is reduced by 1/4 inch on each side, so it ends up about 3.25 inches deep. I used a bit of inexpensive 5/8 inch aluminum towel rod as a crossbar, so the middle plate is reduced to 2 5/8. Use the leftover bits as glue blocks. Test fit with the head and then glue up.
Step 10: Cutting the Front and Back Plates
The front and back plate are just corrugated cardboard, dressed up with a bit of textured paper. The tricorders in the original series have a variety of surface textures -- haircell kydex, vinyl, leatherette -- but mine is real imitation Gorn hide. I cut the "delta moldings" out of cardboard as well. My back plate is about 5.75 x 6 inches, and the front plates are 5.75 x 3.75 and 5.75 x 1.75. I coated each plate with a layer of glue stick, and used the rounded handle of a small screwdriver to burnish the edges of the molding design. At this time you should also cut some door handles out of the aluminum towel rod stock. In the original series there are a couple of variations. Mine are about 1.5 x .5 inches, which is a little large. Cut some slots for the handles and dry fit. The doors on my tricorder are non-functional, but you could hinge them and construct the interior compartments if you have the inclination.
Step 11: Painting
Prior to painting I mounted some 1 3/8 screw eyes on the sides, slightly offset from center to avoid hitting the hinge slots. Next, I did final sanding and prep, masking off areas like the hinge slots, hinge pin holes, screw holes, and glue areas. I temporarily affixed some screws on the body as standoffs to aid during painting. You need to prime first. The textured paper I used had a plastic coating, so I coated it with shellac, which tends to stick to most surfaces, and acts as a primer for most paints. I shellaced the rest of the parts as well, and then finished up with a couple coats of semi-gloss black.
Step 12: Final Assembly
First, finish the head. Wrap your phone in a bit of plastic wrap for safety, then glue in the cardboard box. Use a black marker to color in any exposed areas that you had masked off, including the hinge slots, screw heads, etc. Trim the hinge pins to the correct length, insert the head into the body, and press fit the pins. I didn't use any glue on the pins -- it makes it easier to remove the head later if necessary.
Use hot glue to mount the aluminum cross bar and the front panels. Hot glue the door handles, then close up the back panel.
Step 13: Details
I used aluminum tape to wrap the edges of each side -- just cut it into 1/8 inch strips. I also used it to construct a bezel for the display. I just applied it to some thin cardboard and press-fit it into the head. I super-glued a bead on the 1/16 dowel that activates the home button, and added some plastic screen over the speaker. The hardware store had some light aluminum sheet that would have looked better, but I was a bit pressed for time.