These chess piece toppers are designed to be used with a base made of some other material to reduce 3D printing costs. Wood, stone, clay - whatever you can make. Make your base with a 0.25 inch diameter hole into which each topper can be glued or epoxied. The pegs of the toppers are drawn as 6.3 millimeters (or 0.248 inches) in diameter and might require a small amount of sanding for the best fit in the hole. The scale of the pieces is for a larger King height of around 3.75 inches, but since you're making the bases you can adjust both the heights, diameters, and shapes of the bases to your satisfaction.
In this kit the toppers are all unconnected from each other so you don't need to cut individual pieces from sprues. It also allows fabrication of the toppers in metals if money is of no concern. It is not the most expensive option for white natural versatile plastic but gets very pricey for the dyed options. In those cases you're better off using one of the other sprued arrangements.
Hints (as of this writing):
Purchasing the two U-shaped sprued kits of toppers is cheapest for dyed options such as black versatile plastic.
Purchasing toppers as pairs (pawn & pawn, rook & rook, etc.) is cheapest for white natural versatile plastic.
Always check for the cheapest arrangements of toppers just in case Shapeways implements a price change.
Remember, you'll need two sets of 16 pieces, one set for each player. Note that you can also paint your own chess sets different colors to save on cost. Shapeways charges a lot to colorize the versatile plastic material.
One last thing. An identical set is available but comes with an extra queen. It is available at this
link:
https://www.shapeways.com/product/XQTHHDWWD/chess-piece-toppers-16-plus-extra-queen?optionId=199761457&li=shops