I can timber frame a puritanical cave man waterbed from my standing timber and I will do so if there is a woman who wants to love me in it.
Waterbed mattresses are inexpensive and optimally have perhaps four layers of foam inside. I need my woman to stipulate mortice and tenon joinery or the half lap joinery pictured, or to say if round or semi round logs scribed with a veritas scribe are preferable.
Additionally, my woman will need to choose the species of our cave waterbed lumber and specify the lumber preparation process and the joinery that will work best with that species of tree. There are also considerations pertaining to the biometric dendrology and anthropocentric histories of our locale.
If I had a wife, I could man up and ask my neighbors at Mooressawmill.com for custom oak timbers and board foot lumber in any dimension a Connecticut native oak tree can provide, and Doug Moore would undeniably mill perfect heavy dimension oak timbers. Or, I could invest in a good axe or maul, and in a second broad axe with a custom steam bent handle for hewing, from Gransfors Brux, and then weld or forge the log holding spikes with my ferriers forge and anvil. I know how to hew logs and scribe the axe cut joinery without splitting my right shin in half like a riven sapling.
I don’t want to pit sawyer oak, that’s for certain, but I have dreamt of an automotive pit since youth and only recently found affordable lifts at Eastwood.com
The only other option for prepping my standing timber might be a Walmart Alaskan Sawmill with a Husqvarna Rancher or slightly larger saw that has a bar that matches the Alaskan sawmill appropriate for the Connecticut oaks my wife and I will cruise for with my Biltmore Stick.
Finally, the primary consideration in building a heavy timber or round log frame puritanical cave man waterbed would of course be the feasibility of wood pegging the timber elements permanently together in the bedroom after mill sawyering, pit sawyering and hewing, or the Alaskan process; once our carpentry in the garage has been completed.