I need assistance designing two structural models for a helmet padding experiment. One model will use a hexagonal $($honeycomb$)$ infill structure, and the other will act as a control $($solid or grid$).$ These designs will be tested under compression to evaluate their energy absorption and failure behavior. Here are the specific requirements and details for the models:

General Requirements:

Bounding Dimensions:

All models must fit within a cuboid of dimensions: $10$ cm $10$ cm $2$ cm $($height represents helmet padding thickness$).$

Material Volume:

Both designs must have the same material volume $($relative density $=30\%,$ approximately $16\mathrm{.}97$ cm$^3).$ Adjust wall thickness, hexagon size, or spacing as needed to match the target material volume.

File Format:

Provide the designs as STL files compatible with $3$D printing.

Design Specifications:

$1.$ Hexagonal Infill $($Honeycomb$)$:

A hexagonal infill pattern with:

Hexagon Side Length: Approximately $1\mathrm{.}5$ cm $($adjustable if needed to achieve the target material volume$).$ Wall Thickness: Approximately $1\mathrm{.}5$ mm$.$ Ensure the hexagons are evenly distributed and fit entirely within the bounding dimensions $($no partial hexagons at the edges$).$ Maintain structural uniformity for fair compression testing.

$2.$ Control Design:

Option $1$: Solid Block

A fully solid cuboid with the same dimensions and material volume as the hexagonal infill.

Option $2$: Square Grid Infill

A simple square grid with:

Square Side Length: Approximately $1\mathrm{.}52$ cm$.$ Wall Thickness: Approximately $1\mathrm{.}5$ mm$.$

Ensure the material volume matches the hexagonal infill design.

Additional Notes:

The models will be tested under compression using an Instron machine to measure force$-$to$-$failure and energy absorption$.$

Prioritize accurate material volume matching to ensure fair comparison between the hexagonal infill and control designs.

Symmetry and uniformity are critical to the experiment.