Since I have been practicing tenkara I have used several different line spools and I will share today my definitive opinion about some of them.
This post only reflects my opinion based on my experience of using these spools, it is therefore possible that other tenkara anglers have different opinions about these products.
The Tenkara Pyrénées spool accompanied me often. This cork spool is very light and strong but as I do not wear waders anymore I realized that its thickness is too important for I keep it in the pockets of my pants. The major drawback for me, in addition to the thickness, isthe axial hole which is too small to allow a secure locking of the spool on the handle of my favorite tenkara rods.
The styro-foam spool...I had purchased 8 of these in a clar plastic case on e-bay and I must say that for the super cheap price I did pay I had what I deserved! The 8 spools were destroyed in 8 outings. I always put my spool in my pants pockets and these ones were quickly so squeezed that they had become unusable. I personally think it is a shame that more and more tenkara tackle shop sell these to their customers at high prices when this is ultra cheap on wholesale and low quality. Avoid this #rap!
Eclectic Angler is the only company to offer a 3D printed spool that I like for its small dimensions (only 48 mm in diameter!) and light weight (0.34 oz)! It is deep despite the small diameter but on the other hand the axial hole is quite small, at least too small for I can lock it on the handle of my favorite tenkara rod. It is exclusively sold on the Eclectic Angler website for 10 US dollars.
The Raji Leica spool has the advantage of an incredible strength and convenience. It is not thick (13 mm) and lightweight (12.5 grams). One can use a tiny metal rod to hang the fly but in this case I advise not to try to put the spool on the rod handle. This spool has many notches and very dense foam so there are a lot of possibilities to manage your fly and your line. Like many other tenkara line spools you will have to write on it to identify the line stocked. All in all this accessory is very good quality and not expensive.
My favorite spool! The Meiho Shibamaru is very convenient with many notches to manage your fly and your line. It is not deep but one will stock a 20 ft line (level or tapered) without problem. This spool is incredibly strong, only 14 mm thick and pretty light (0.61 oz). It is sold in packs of two including stickers to identify the line stocked on the spools. I also like this spool because I can "lock" it on the handle of my favorite rod; that is how I carry my line when I go fishing or when I walk from a spot to another.
Tenkara is a rod, a line and a fly. A good spool in my opinion is convenient and strong. It is the product that will avoid replacing cheap and bad quality accessories by other cheap and bad quality accessories.
This post is based on my experience with one of the rare useful accessories in tenkara and you might not agree with my choices. It's your right!