you don't have to get the kit with the flex shaft or right angle adapter (i have neither, but want them). but they come in handy. it'd be cheaper without if you have a budget (like i do ;-))
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you will go through the "regular" cut off discs like crazy. you will go through sanding bands like crazy. get plenty of those.
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make sure you get the tool with the variable speeds. either with the digital read out (professional) or the regular red switch. the digital one is more customizable with respect to speeds, but the regular red one is what i have, and it's fine with me. get used to each rotational speed. start slow to get a handle of it, and go faster (like the middle notch) since you don't need the highest speed.
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NOTE i have the "craftsman" labeled "dremel" which is obviously made by dremel for sears.
and black and decker has a rotary tool like the dremel too. get what you can afford. but don't ignore all of what i wrote above.