Of all tools, those used for measuring and marking affect the quality of a project more than all the others combined.
Rulers, gauges, dividers, bevels, tapes, squares, calipers, micro-meters, even hand-held computers make measuring easier and more accurate than it's ever been. Some of the tools date back to ancient times, whereas other recent innovations will not be affordable for sometime yet.
The tools you need depends largely on the project and materials you're working with. A home workshop should have at least some of these: a 16-foot tape measure, a 6-foot folding rule, a scratch awl, a steel straightedge, level, plumb bob, tri-square and, if you work on your car, feeler gauges.
High on your list of additions to this starter group should be a marking gauge, rules and several squares including a combination, tri, framing and sliding bevel square.
Without measuring and marking tools, it would be nearly impossible to build even the simplest project. Fortunately, most of these are relatively inexpensive and those needed for a one-time project can be rented, borrowed or improvised.
Whether you are trying to build a barn or a birdhouse, or level a bookcase--here are some of the measuring tools that will make the job go easier and better:
Sixteen-foot tape measure--Every home or apartment dweller needs one. You can save a few dollars by buying a shorter rule, but there will be so many times when you'll want one at least this long that this would be a false economy.
Six-foot folding rule--This is handier than the tape and is therefore worth getting, but it could be eliminated from a minimal kit.
Scratch awl--If you want to make an accurate line for sawing a board, this needle-sharp steel rod does a better job than a pencil and can also be used for making holes in soft wood for starting screws.
Steel straightedge--Get one at least 18 inches long for accurate measuring. Stainless steel doesn't rust so it is well worth the added expense.
Level--Small levels are cheap and handy, but one 12 or 18 inches long makes leveling clocks or appliances easier. A high-quality metal level can also substitute for a straightedge if all you need to do is draw a straight line.
Plumb-bob--Sure, you can hang a ballpoint pen on a string, but a real plumb bob is steadier and inexpensive. You can also get one with a reel for a chalk line, which is worthwhile if you want to build a deck or do any construction.
Tri square--Sooner or later, you'll want to draw a square corner or cut a board accurately and a tri square is the tool that makes it easy. Again, inexpensive small ones will do some of the time, but a larger, high-quality square is one sign of a capable craftsman.
Feeler gauges--This set of steel fingers of differing precise thicknesses ranges from .001 inch to .02 or thicker. You use these to make accurate adjustments of the space between two parts in a car or other precise machinery. They're both inexpensive and indispensable. Round wire feeler gauges are used for setting spark-plug gaps.
Once you get beyond the minor requirements of the home, you begin to need the tools of the trade you are involved with. Serious craftsmanship in any field calls for high-quality, professional and sometimes expensive measuring instruments.
Among those you may find useful are:
Sliding bevel square--Similar to a short T-square with an adjustable crossbar locked by a wing nut, this ancient tool is essential for woodworking. Use it to set up accurate angles for dovetail joints and other closely fitted parts in cabinetry.
Inside and outside calipers--Ranging from rough stamped steel to screw-controlled, accurately ground precision instruments, calipers measure sizes and help you transfer them accurately when copying any object. If the tips point outwards, they measure inside dimensions and if the tips curve inwards, they take outside measurements. Calipers are particularly important for wood turners who use them to measure the diameter of a work piece while it's chucked in a lathe.
Marking gauge--Lay out wood joint lines-of-cut with this adjustable tool. Designed for marking with the wood grain, the gauge scribes a very fine, precise line that is more accurate than a pencil line. Good ones have a single spur and an adjustable double spur for scribing two parallel lines simultaneously.
Digital measuring devices--These give numerical readouts on liquid crystal diode screens and make taking measurements a lot quicker. However, you can count on paying roughly three times as much for the micrometer, caliper or special gauge that has this feature compared with the plain version. If you do not really need speed that badly for your home projects, less expensive, old-fashioned measuring devices do as well if you use them carefully.