If the slats are too wide use a powered saw of some kind. We recommend changing the blade to one that doesn't have much bite on it. Go slow with the saw. If you are using a hand saw try using a hacksaw rather than a standard carpenters saw. Just remember that in order to do a good job you must take your time and go slow.
1. Align the slats so that they are even.
2. Using a clamp or rubber bands, secure the slats together into position.
3. Wrap the slats with masking tape to prevent chipping.
4. Measure where you want to cut and mark a line with your pencil. Make sure that the masking tape covers the entire area you are cutting.
5. Lay them on the saw and line up the blade where you need to cut. Make sure that you take into to account the width of the blade.
6. Make sure that the headrail and the clamp is not interfering with the saw. You can slide the headrail to the side out of the way.
7. Slowly cut through the tape and slats.
8. Remove the tape and clamps or rubber bands.