Modifiers matching pipe:

• main,
• plastic,
• underground,
• larger,
• standard,
• sized,
• rigid,
• decorative,
• flexible,
• concrete,
• unusual,
• metal,
• ferromagnetic,
• metallic,
• old,
• inside,
• smaller,
• additional,
• exposed,
• cylindrical,
• resilient,
• hard,
• fixed,
• vertical,
• temporary,
• nonmetallic,
• thicker,
• conventional,
• hollow,
• industrial,
• ceramic,

Simple categories matching rigid:

• surface,
• block,
• material,
• carrier,
• alteration,
• object,
• group,
• connection,
• implement,
• ground,
• structure,
• appendage,
• tip,
• instrumentation,
• container,
• article,
• airfoil,
• plant,
• devices,
• pavement,
• insulation,
• particle,
• strip,
• coil,
• splint,
• aggregate,
• paper,
• web,
• body,
• item,
• substrate,
• connector,
• rock,
• medium,
• adhesive,
• fiber,
• metal,
• post,
• package,
• resin,
• filler,
• covering,
• feature,
• measure,
• fibre,
• hitch,
• product,
• fixture,
• architecture,
• pipe,
• cloth,
• appliance,
• form,
• floor,
• support,
• cement,
• stick,
• display,
• system,
• panel,
• component,
• frame,
• fastener,
• matrix,
• bottle,
• cutoff,
• protein,
• polymer,
• tool,
• textile,
• case,
• organ,
• base,
• rod,
• document,
• boundary,
• instrument,
• finish,
• obstruction,
• matter,
• plastic,
• fabric,
• motion,
• sector,
• means,
• shape,
• fixing,
• watercraft,
• thermoplastic,
• member,
• layer,
• organs,
• change,
• class,
• piece,
• part,
• movement,
• substance,
• device,
• mechanism,
• cylinder,
• cover,
• food,
• tube,
• unit,
• plate,
• armour,
• dressing,
• space,
• sheet,
• portion,
• casing,
• profile,
• foundation,
• vehicle,
• representation,
• construction,
• entity,
• deck,
• molecule,
• monomer,
• gel,
• hanger,
• wall,
• sphere,
• element,
• macromolecule,
• lining,
• foam,
• deposit,
• boot,
• thread,
• sorbent,
• tissue,
• obstacle,
• solid,
• transformation,
• bed,
• luggage,
• packing,
• transparency,
• barrier,
• tubing,
• mineral,
• shaft,