@dogberry The Standalone Tonearm Pod I designed after looking at a multitude of Designs was to have an approx' 4 Inch (100mm) OD, Hollow Phosphor Bronze Billet with a Spiked Base mechanically attached. At the time I recollect the Billet could be acquired with perfectly flat Top and Base as an additional cost to the purchase for approx' £80. From the same Machine shop a matching OD Base Plate of approx' 20mm thickness was between £10-£20 depending on Aluminium, Brass or Gunmetal.
A proportion of the Base of the Billet was to be filled with Lead Shot. up to the level where the Billet Wall was bored to allow the Tonearm Signal Wire or Cable to exit the Void.
The Top Plate was to be a Multi-material approach to create different damping and dissipation interfaces. At this time Delrin was an early material to be tried, as Acetal was respected as a Platter Material.
If I were to adopt this method today, I would work much closer to Densified Wood as the Bulk of the Structure.
The Tonearm Pod I regularly witness in use has been Bespoke Produced by the same Machining Company that produced the SP10 R's Aluminium Plinth.
The Design is close to mine, but has a Aluminium Hollow Billet and Thick Brass Base and Spiked Feet, Lead Shot in the Void. There are options to use a alternative Top Plate Material, but Aluminium is used at present.
The owner of the TT>Tonearm, is already starting to express a curiosity toward Densified Wood, and I suspect this may start with the Tonearm Pod, as my owned 75mm Thick Board has been discussed within the HiFi Group as to what could be done with a Off-Cut.
I am sure I have offered a Off-Cut of this same material on this forum to another member for the use as a Tonearm Pod.
If you develop the curiosity yourself let me know and I will see how I can assist with your request.