Problems milling this model

[m_c]

Thanks, it's a shame, I'm not massive on 3d printers, always feel a bit disappointed with quality compared to router.

It depends on what your requirements.
Most 3D printers are FDM (Fused Deposition Modelling) aka use rolls of filament, which is pretty good for large items, but isn't ideal for smaller items where you want a lot of detail. It is doable, and I've produced some pretty good models, but it's a slow process. The major benefit is you can print with a wide selection of materials, without any specialist equipment.

With a Resin printer, they use a UV/Photoelectric system to cure a pot of resin, adding a thin layer at a time to the model. The big benefit is layers are a lot thinner than FDM, giving far better details, but it uses specialist resins, and models require excess resin washed off.

If I could justify it, I'd like to try a Creality LD printer as the small ones aren't that expensive (~£150), but I've got enough toys to play with just now, and my Ender 3 does everything I need at the moment.