For the past few weeks, I've been tinkering on making some male-molds for future ballasts. I've 3D printed two male-molds for Sun Wind HF style torpedo bulbs, one slightly smaller than the other to make a lighter weight bulb if desired. And then also I've worked on a shaped ballast mold for the current Wampum VM that I'm building. Today, I finally took a big gulp and filled the molds full of refractory cement. Now I'll let it cure for a few days and then attempt to take off the molds and see how they look. Then I'll let the cement cure for a few weeks, occasionally in a warm oven, to fully cure before I attempt to pour lead in them. Here are two pictures of the molds in boxes that I framed around them. They have also been smeared liberally with Vaseline as a release agent.  I'm going to wait several days before trying to remove it. Gulp... Here are the two molds after being filled with refractory cement. I bought a 25 lb. tub and used it all. I...

I'm in the process of thinking, yes... just thinking, about making my own ballast for both the Sun Wind Hf and for the upcoming Wampum III, both Vintage Marblehead sailboats, but using two different styles of lead ballast. The Sun Wind HF takes a torpedo style bulb. I 3D modeled one in Sketchup Pro 2017, and from there exported an STL file that I used in one of our 3D printers at school (I'm a teacher and the CTE teacher actually printed it for me). Here is what we ended up with... two identical male molds: Here is what the bottom of one of them looks like: 3D prints are a bit rough, and if I used them straight they might stick to the cement too well. So I'm coating them with thickened epoxy and will then sand them down. I'll then wax them before using them. The idea is that I will sink these into a container of refractory cement and let it harden, will remove the molds, and then let it cure for a long time (weeks). The concrete will probably also take a t...