This sluice box has a mixture of riffle to catch every last bit of gold it is a 4x16 sluice but can easily be scaled up or down to fit your needs. It will print with no supports if positioned right.
STL (Stereolithography, filesize: 688 KB), OBJ (OBJ, filesize: 852 KB), FBX (Autodesk FBX, filesize: 351 KB), USDZ (USDZ, filesize: 199 KB)