2 - 8' 2X4 beams
2 - 6' 2X4 beams
2 - 4' 2X4 beams
8 - 5 and a half inch 3/8" bolts
4 - 6" 3/8" bolts
24 - 3/8" washers
12 - 3/8" tightening washers
Step 1: Angled cuts.
Step 2: Drill the holes
The angled beams will be "sandwiched" between the two 8' beams and the bolts will go through all three pieces. To make sure I had a straight hole for the bolt to go through all three I laid down all three four pieces on the floor just as they would when standing and drilled once through all the wood. As you can see in the picture I made the holes 1" from the edges.
I should also note that the angled beams are not flush with the base beams. This is because the base will rest on top of the 4" pieces and hence be elevated about 2" from the floor. Having the angled beams reach all the way to the floor adds stability. You could also cut a "bed" in the base beams to fit the two 4" pieces so that the base would rest on the floor.
The other holes to be drilled are holes for they eyebolts where the hammock will hang, and the holes to secure the base to the "feet" the two 4" beams.
Step 3: Assembly
After using it a few days I've thought of a couple of improvements. The angled beams flex quite a bit when the hammock is rocking so I think some tensioners running from the top of the beams to the edge of the feet would increase the stability. however they could become tripping hazards!
I should also note that I choose these dimensions based on my hammock's length.
So far it's held pretty well up to 200 pds.