Why not? We're 3-D printing jet engine parts already.
https://www.ge.com/reports/mad-props-3d-printed-airplane-engine-will-run-year/
An interesting aspect of 3-D printing is that you can print not just a part, but an assembly. It's a common printer demo kind of thing to print a chain or other interlocking parts. If you could print the bearing materials, you could print a crank inside a block, with no removable main caps. Instead of rebuilding an engine, you just scrap it and print a new one - especially with external overhead cams.