Estimating Material Weight & Load for Diorama Bases
A diorama base looks simple, but the wrong material choice can leave you with a project that is impossibly heavy to move, warps under its own weight, or cracks a resin water feature months later. Estimating volume and weight before you pour or pile anything is one of those five-minute checks that saves an entire afternoon. Enter your base dimensions and pick a material to see the volume and approximate weight instantly.
How the estimate works
Weight is simply volume multiplied by density. The tool multiplies length, width and depth to get volume in cubic centimetres, then multiplies by the material's typical density in grams per cubic centimetre. Dry sand sits around 1.6, gravel around 1.5, cured polyurethane resin close to 1.15, and plaster roughly 1.2. Expanded foam is featherweight at around 0.05, which is exactly why it is the go-to core for large terrain — you carve the bulk from foam and skin it with a thin, heavier detail layer.
Managing resin pours
Resin and epoxy for scale water are where weight and heat matter most. Deep single pours trap exothermic heat, which can crack the resin, yellow it, or warp a thin base. Knowing the volume up front lets you plan pours in shallow layers — most epoxies specify a maximum depth per pour, and staying under it is the secret to crystal-clear results. The weight figure also tells you whether your base needs internal bracing before the pour.
Ballast, gravel and groundwork
Scale ballast and gravel are usually glued down with dilute PVA, so the dry weight above is close to the final weight once the glue dries. If you are filling a large volume, consider a lightweight filler core to keep the piece portable — a big all-plaster base can become surprisingly back-breaking. For shelf and cabinet displays, check that your chosen shelf can safely carry the kilogram figure, especially when several dioramas share the same surface.
Use this estimate alongside the Scale Converter to keep your groundwork proportional, and plan your base structure before committing expensive resin or plaster.