# Designing for Resin: A Few Things Slicers Need > Sculpting your own miniatures? What a resin slicer needs that a render never shows: one closed solid, outward normals, real thickness, the right file and scale. Source: https://local3dprinting.com/blog/design-for-resin Published: 2026-10-16 If you sculpt your own miniatures, there are a handful of things resin slicers care about that sculpting software doesn't. None of them show up in a render, and none of them say anything about the quality of the sculpt. They're a different set of requirements, and they're all quick to check once you know where to look. This one's written for people making their own models and provides some things to consider when getting your project ready for printing. ## Why slicers want a single solid Most of what follows is one idea in different forms. A slicer works by asking the same question about every point in space: is this inside the model, or outside it? To answer that, the mesh needs to be a closed solid with a clear inside and outside. Anything that leaves the question ambiguous is where problems tend to come from. A render never has to answer that question, which is why these things can sit in a file for a long time without anyone noticing. ## Separate pieces that look joined A figure often gets built in parts. A head, a couple of arms, a cloak, a weapon, a base, each pushed into the others until it reads as one model. On screen that's finished. To the slicer it's several separate shells sharing the same space, and different programs handle that differently. Some union them quietly, some generate internal walls or unexpected voids, and some stop. That inconsistency is usually why a file that behaved perfectly well on one machine comes back with problems from another. A boolean union or a voxel remesh before export sorts it out. In Blender, a remesh at a sensible resolution is often less work than tracking down boolean errors. ## Normals, and why they're easy to miss Faces have a direction, and the slicer uses it to work out which side is solid. If some of them point inward, it gets contradictory answers. This is one of the genuinely invisible ones, since a viewport will look completely normal either way. Selecting everything in edit mode and recalculating normals outside takes a moment and rules it out. ## Capes, flags, and other thin things Anything modeled as a sheet has no thickness. Cloaks, banners, leaves, loose fabric. Resin can't produce a surface with no depth, so these want real thickness before export. On a 32mm figure, somewhere around half a millimeter is a reasonable minimum, and a little more where an edge is unsupported. ## A note on file formats OBJ is worth avoiding for print work, mostly because of units. An OBJ file carries no unit definition at all. A cube in one is simply two units across, with nothing recording whether a unit means a millimeter, a meter or an inch. Combined with Blender's default scene scale, that's behind most of the cases where a model arrives a thousand times larger or smaller than intended. OBJ also allows several named groups in one file, which can fragment a model, and it carries material and UV data that printing doesn't use. STL works well here. 3MF works better, because it states its units outright and takes the guesswork away. Setting the scene to metric millimeters and applying scale before export handles the rest. ## How much detail survives at final scale Resin resolves a great deal more than FDM, though not infinitely. On a 28mm or 32mm figure, raised detail below roughly a third of a millimeter tends to soften away, and thin elements like spear shafts, blades and antennae hold up better at a millimeter or more. Below that they can flex during curing and break during cleanup. Sculpting at high resolution is no problem at all. It's just worth a look at the detail at final scale before exporting, since things that read clearly at 150mm can vanish at 30mm. ## Hollowing and supports These two are easier handled at our end, and it saves you a step. Hollowing needs to match the orientation we choose, and a model hollowed without drain holes can trap uncured resin and form a suction cup against the plate. Supports are tuned to a particular printer, resin and exposure, so a file supported for one setup rarely transfers cleanly to another. Solid and unsupported is the most useful thing you can send us. ## A quick check before exporting Blender includes a 3D Print Toolbox addon, switched off by default, which you can enable in preferences. Running Check All flags non-manifold edges, intersecting faces, zero-area faces, loose geometry and thin walls, which covers most of what's above in one go. Fix anything it reports, apply your modifiers and your scale, then export. ## What to send us One solid mesh, STL or 3MF, at final scale, unhollowed and unsupported. Let us know the intended height and we'll confirm it matches what arrives. Resin is quoted on request, not through the quote form, so [tell us about your model](https://local3dprinting.com/?topic=resin#contact) and we'll get back to you within an hour or two.