Design and construct a simple hexagonal redwood bench around your family tree--the geometry of building the hexagonal bench is easier than a circular bench yet provides equal sitting comfort and practicality from all sides because it is symmetrical. Build the bench in sections with leg/supports spaced to avoid the tree's roots and then assemble it around the tree.
Plan the dimensions of the hexagonal custom tree bench to encompass the tree trunk without damaging it or impeding its growth. Set your power miter saw for a 30-degree angle and cut the first row (inner row) of seat boards.
Lay two planks parallel to an inner seat board, separated with 1/4-inch spacers. On both ends, extend a 30-degree cutline from the first board across the other two. Cut six sets of inner, middle, and outer planks in this manner.
Build six tree bench supports having two two-by-six legs sandwiched across the top by two one-by-four cross braces. Secure them with galvanized carriage bolts, washers, and nuts. Tighten the nuts with a socket wrench, compressing the wood slightly.
Join two seat sections, drilling pilot holes beneath to screw a support directly over the joint and one at both ends of the assembly. Make two assemblies, reserving the remaining two individual sections for installation once positioned around the tree.
Turn the two bench assemblies upright. They are not yet rigid, so drill countersunk pilot holes and screw through the bench top into the support cross braces below. The countersunk screw heads will lie beneath the surface and protect clothing.
Level the two bench assemblies around the tree, leaving gaps of the exact length for the two remaining seat sections. If necessary, remove soil to level the ground for the tree bench, but avoid the tree roots.
Drop remaining tree bench planks into position. Drill countersunk holes to drive screws through the bench top into the support cross braces below. Remember to leave a 1/4 inch space between boards to allow for wood expansion and water drainage.
Coat redwood with sealer to extend the tree bench life, keep it looking good, and prevent the top from weathering and becoming rough. All these actions will lead to less maintenance labor and make the bench more comfortable as well.