Bicycle stem / steerer top cap with a decorative cover for 1 1/8" steerers.

CR-10

Doesn't Matter

Yes

solid, or at least several wall and top layers

Two parts. The top piece is just a decorative piece that hides the M6 bolt to the compression plug or star nut in the steerer. The decorative top has a 22 mm x 3 mm recess in the bottom and friction fits on the base. If you want to actually use the printed top cap base piece to set the preload on the headset you should print it strong. I printed it solid.

Snap out the supports, install the base with bolt from stock top cap (usually M6 x something), snap on the decorative cover. If you insist on printing it thin and light, you could use a normal metal top cap to set the preload, tighten up the stem pinch bolts, then remove the metal top cap and install the printed base as a decorative piece, but I wouldn't want to do that in case you ever need to adjust your stem on the road.

Converted logo from buddies shop to svg and imported as sketch in Fusion 360. Had to recreate most of the circles and some of the curves to close microscopic gaps in the geometry, Then I just created a rough copy of one of my metal top caps and played with the geometry. Iterated until I was happy.