First remove the screws that hold the two halves of the toy together, and cut the battery wires loose from the battery compartment, and carefully remove the electronics from the toy. The speaker and the board are glued in place, But a small hobby knife will easily cut the glue loose. You will also need to carefully bend the tabs on the battery terminals to remove them from the toy.

The next step is to trim the board. There is a 1/8th inch on the board that has no traces on it, and it must be removed to fit in the model. It is also helpful to round off the corners of the board. Care must be taken not to damage the wires or components. You can achieve this with sand paper or a dremel tool.

With a small saw or hobby knife you need to cut slots on the battery compartment of the model. This will allow the installation of the battery terminals

Next you will have to trim the terminals as shown in the example using a file or dremel.

The next step is optional for now. I just find it easier to glue the board in the phaser to aid in keeping the parts together, and trimming wires to length.
You will also need to determine the best way to orient the board in its hole. There is a resistor on one side, and a small capacitor on the other side that tend to make this a challenge. Usually having the resistor on the speaker side works best.
Also you can drill a small 1/8th inch hole Forward in the speaker hole if you would like the phaser to be louder. It is important to drill the hole forward to keep your finger from covering it when you fire it.

Next you will start trimming, and resoldering wires. We will start with the Red+ wire, and The black- wire. Trim them to fit where the terminals are, and solder them to the terminals. Also the speaker wires are too long and should be desoldered from the speaker, and trimmed and resoldered to the speaker. You can leave them long, But you will need to bundle them up inside the phaser. It is much better if you can shorten them. At this point you should be able to install some batteries, and test what you've done so far. The best batteries for this can be found at most stores(LR-44 Button Cells). Michel's, and hobby lobby has them cheap. Usually 6 for 99 cents. They are commonly used in things like laser pointers. It is best if you insert the batteries, and remove them after each step to check your progress. Just do not leave them in the model when you are cutting wires. This will prevent shorting out the circuit.

The toy phaser has two sounds, and the cricket model isn't big enough for the selector switch. This means you must select the sound you want to use. The best sound of the phaser firing is produced by connecting the blue, and purple wire together. Then I solder the connection, and either tape the bare wire with electrical tape or use a small piece of shrink tubing.

It may be necessary to route out a small indent in the center of the emitter if you are using a large LED. Small LED's do not require this mod. You can accomplish this with either a dremel or a drill.

I then shorten the wires on the button so that the wires are not folded up inside the phaser

Next I glue in the power bar, and the button plate.

I then glue the two body halves together making sure the trigger button is not left inside. Then you can test fit the emitter. It may be necessary to trim it slightly below the LED hole to accommodate the speaker.

After the proper fit is accomplished. You are ready to glue on the emitter

At this point you can glue the button to the body making sure it is centered under the thumbpad.
You are also ready to Fill in the seams with puddy, or bondo

The next step is to mask off the emitter, and power bar, and prime the phaser with a sand, and fill primer. After the primer dries You can sand it to a smooth finish, and start painting

Before or after you prime you can also finish the thumbpad. You need to glue a small piece of styrene on the underside of the thumbpad so that it will be just over the button when it is in place. Trim both the front and back of the tab so that it looks like a wedge. This will make it easier to install, and remove the thumbpad when you need to change batteries. Make sure the wedge fills the empty gap between the pad and the button. Its better to make it thick at first than too thin. You can fine tune it until it fires smooth with a piece of sandpaper or a small file

You now can paint it