Here is a muti-piece Minecraft ore block I made. The pieces fit together fairly tightly so you shouldn't need to glue it or anything.
The block stand is mainly in case you want to add a light into the block and it's too high up. If you use the stand the light sits lower and looks better depending on your light fixture. I bought 5 2.75" light pucks for about $15, but any light you can fit in there should work fine.
Updates:
3/11/2021:
Ore_Stand.STL | 2.4KB | |
Ore_Stand_With_Wire_Slot.STL | 3.0KB | |
Ore_Top.STL | 30.6KB | |
Ore_Wall.STL | 33.3KB | |
Ore_Wall_With_Wire_Slot.STL | 34.1KB |