There will be many opinions on that. My opinion, either a table saw or radial arm saw, a small drill press, hand drill, wood clamps,wrenches, small belt sander, random orbital sander, and misc other hand tools.
++++++++++++++++++++++++++ It is still the best bang for the proverbial buck that requires the lowest skill level and the smallest budget to get started. For the cost of a Zodiac horizontal stab "starter kit" you can buy enough timber, foam and glue to keep you going for a year (if you really work at it). You will acquire skills (and tools) that will make you extremely popular with the good lady and provide enormous self satisfaction. Don't buy anything from anyone (including RR) until you have bounced it off someone that has already built one or is at an advanced stage of doing so. Don't waste much time pondering about the engine for another year, maybe two. Things are changing all the time, by the time you get there, you will have several options ranging from a $19.95 DIY manual to off-the-shelf and ready to run; $1500 to $5000; VW's; Corvair; Hog are already there. Remember the saying:- you can teach a wise man anything (and a fool nothing) - ask /listen. Maybe add a bit to uncle Larry's tool list: table saw or radial arm saw, wood clamps, a small drill press, wood clamps, hand drill, wood clamps, wrenches, wood clamps, small belt sander, wood clamps, random orbital sander, wood clamps and misc other hand tools (and maybe a few wood clamps). Also check with your neighbours - ask them if they have any wood clamps you can borrow some days. Good luck Steve J