This is a pottery batt system to fit a wheel with pins at 10" centres.  One side of the base is slotted to give a bit more leeway.  Or you can use a battmate. My holes are 10mm - my pins are 10mm so there is no clearance.  To be revised on next iteration of base.

The tiles are made with very limited clearance to the batt so make sure you're printing these on the same printer, or have two that are VERY accurate.  The hole is 180mm across, with 10mm radius corners.  The tile is 179.5mm across so only .5mm spare.

Making this I discovered my printer was printing a very slight parallelogram rather than a square.  Only 1mm over 180 but enough to make the tiles only fit two ways into the slot. Also the circular base isn't a circle!

Consider the surface when you print.  I tried ironing the surface but it came out worse than just printing the top and bottom slowly.  The clay sticks very well to a slightly rough surface making life easier for centring anyway.

These are not cheap to print but they are still cheaper than the terrible MDF batts and even cheaper than the super high quality wood or aluminium batts.

Update - It's been more than a year and I've been busy elsewhere.  I've uploaded a STEP file from my Fusion project for anyone that wants to make use of this for their own purposes.