To remove the popcorn ceiling, start by protecting all the surfaces including floors and walls that you do not want to get damaged or wet. Since water is used in the process be sure to turn off the electricity at the breaker. Use a garden sprayer or spray bottle if you don't mind refilling often and saturate the ceiling. Use a plastic scraper to remove the popcorn material. As a side note if your ceiling was installed in the early seventies it may contain asbestos. Send a small sample to a certified lab prior to removing. While removing the popcorn, chances are some the joint compound was also removed. To insure a flat ceiling refill the joints and any screw/nail holes with fresh joint compound. Let dry, sand and repeat, to insure a flat surface a skim coat may need to be applied. Prime the ceiling with primer recommend for wallboard and a blank slate is created.
When tackling a home improvement project, always keep an open mind. There are hundreds of design opportunities to accomplish your goals.
When cutting up small pieces for a project, an easier way to doublecheck for accuracy is to measure a number of the pieces at once. If you have four pieces which should be exactly 8 in. long, lay them end to end and measure. This multiplies small errors hard to detect on only one piece. For example, if the four pieces measure 32-1/8 in. instead of 32, then you know that each of the pieces is 1/32 in. too long.
When sawing wood, take time to consider which side of the material to having facing up. Keep the good side up when you are using hand saws, scroll saws, bandsaws, tablesaws and radial-arm saws. Keep the good side down when using a portable circular saws or sabersaws. The principle is to have the tooth of the blade first break through the rough side of the board or panel.