AR 15 base with 4 holes , and threaded grip thread hole , better to do with aluminum alloy

3D printing settingsCarbon-fiber reinforced PETG is stiffer and stronger than standard PETG. It does not degrade or warp significantly in freshwater or saltwater.• Benefits: It offers excellent UV resistance, prints easily, and results in a beautiful matte finish straight off the printer bed.• Drawbacks: Requires a hardened steel nozzle as carbon fiber is highly abrasive.

ASA (Acrylonitrile Styrene Acrylate) • Why it works: Often considered the superior, outdoor successor to ABS. It is highly resistant to both UV light and continuous water immersion. • Benefits: Extremely tough with a high heat tolerance so the handle won't warp if left in the sun on a boat deck. • Drawbacks: Tends to warp more than PETG, usually requiring a 3D printer with an enclosed build chamber.Nylon (PA) / Nylon Carbon Fiber (PA-CF) • Why it works: Nylon is virtually indestructible under mechanical stress and absorbs heavy recoil shocks without snapping. • Benefits: Maximum impact resistance, which is ideal for a high-tension speargun. • Drawbacks: Nylon is highly hygroscopic (it absorbs moisture from the air and water) which will cause it to soften and swell in the water. You must coat the finished handle completely in marine-grade epoxy to make it 100% waterproof.CNC / Wood Milling (Precision for DIY & Workshop Builds)