There are many things a private person cannot import to Thailand without special permission and without the assistance of an experienced freight forwarder. It is true that there are exceptions (UPS, for instance, allowing lithium-ion battery-operated devices), but these are all subject to negotiation with specialized freight forwarders.
You may find this list useful in avoiding customs and police problems.
These are officially not acceptable in Thailand:
Animal Supplement, Beauty Supplies, Candy, Cigars, Food/Grocery, Health/Medical Supplies, iPhone, Apple Watch, iPad, iPod, Lighter, Mobile/Cell Phone, Others, Perfume, Serums, Sprays, Supplements, Tablet, Tea, Hookah and hookah accessories, Medicine
General Unacceptable Commodities
Animals Live or Dead animals, Insects, Reptiles of any kind, Animal Products (Skins, Meat, Fur including Hair Products)
Artwork Any collectible painting, Sculpture or other work of Art Antiques
Counterfeit Goods As per the Customs Law in China, fake/counterfeit goods are not allowed to be shipped out to other countries
Corrosives Aluminum chloride, Caustic soda, Corrosive cleaning fluid, Corrosive rust remover/preventative, Corrosive paint remover, Acid (Hydrochloric acid, Nitric acid, Sulphuric acid, etc.), Substances which can cause severe damage by chemical action to living tissue, other freight, or the means of transport. All corrosive substances are prohibited.
Drugs Cocaine, Cannabis Resin, LSD and Narcotics, Morphine and Opium, Psychotropic substances, Prescription drugs sent for medical or scientific purposes, drugs in prescription quantities may be sent by private individuals in the case of emergencies. Etc
Electronics Laser (as Laser Hair Removals or Laser Pens), Walkie Talkie, Used Laptops manufactured before 2008 (not allowed in Egypt)
Explosives Ammunition, Firearms (including parts), Blasting caps, Christmas cracker snaps, Party poppers, Theatrical flares, Fireworks (Skyrockets, Sparklers, Crackers), Flares, Fuses, Ignites, Nitro-glycerin, Any chemical compound, mixture or device capable of producing an explosive pyrotechnic effect, with substantial instantaneous release of heat and gas. All explosives are prohibited. etc.
Fake/ Dummy Games Toy Weapons, Paint-Ball Guns and BB guns, Antique weapons, Knives and Swords, Fake grenades, Items that could be used as weapons, etc.
Flammable liquids Alcohol, Perfume, Acetone, Benzene, Kerosene, Motor fuels, Battery fluid, Gasoline, Lighter fuel, Cleaning compounds (Bleach, Disinfectants, Laundry detergents, Oven cleaners, etc.), Nail Polish, Paint thinners and removers, Petroleum, Adhesive products (Glue, Silicone, etc.) Turpentine, Solvents, Liquids, mixtures of liquids, or liquids containing solids in solution or suspension which give off a flammable vapor, etc
Flammable solids Calcium carbide, Cellulose nitrate products, Matches (any type including safety), Metallic magnesium, Nitro-cellulose based film, Phosphorous, Potassium, Sodium, Charcoal, Flint lighters, Hydride, Zinc powder, Zirconium hydride, Substances liable to spontaneous combustion. Substances which in contact with water, emit flammable gasses. Solid materials which are liable to cause fire by friction, absorption of water, spontaneous chemical changes, or retained heat from manufacturing or processing, or which can be readily ignited and burned vigorously. etc.
Fragile Glassware, Ceramics, Lighting (fluorescent tubes, neon lighting, x-ray tubes, light bulbs, etc.) Musical instruments, Plaster items (fibred clay)
Gambling Lottery Tickets, Gambling Devices
Gasses compressed, liquefied or dissolved under pressure All flammable compressed gasses are prohibited (Blowlamps, Butane, Cigarette lighters), Ethane, Gas cylinders (Camping gas cylinders full or empty) Ammonia products, Hydrogen, Methane, Propane, etc. Permanent gasses, which cannot be liquefied at ambient temperatures; liquefied gasses, which can become liquid under pressure at ambient temperatures; dissolved gasses, which are dissolved under pressure in a solvent.
Government Issued Documents Including but not limited to Permanent Residence cards, Green Cards, Work Permits, Passports, Driver’s Licenses, Health Cards, Correspondence from respective countries tax authority (e.g., Revenue Canada, Internal Revenue Service, HM Revenue and Customs)
Minerals Fossils, Jewelry, Stones or stoneware, Marble or any stone derivative
Miscellaneous Asbestos, Dry ice (solid carbon dioxide), Magnetized material, Toner (Photocopier), etc.
Negotiable Currency Bullion, Money, Fake/Dummy/Collectable Cash, Payment Cards, Traveler Cheques, Passports, IDs, Stamps, Gift Cards
Oxidizing substances and organic peroxides solids Dyes (Hair, Textile, etc.), Bromates, Chlorates, Components of fiberglass repair kits, Nitrates, Perchlorates, Permanganates, Peroxides, Fertilizers, Weed killers, Insecticides, etc. Though not necessarily combustible themselves, these substances may cause or contribute to combustion of other substances. They may also be liable to explosive decomposition, react dangerously with other substances, and be injurious to health. All oxidizing substances and organic peroxides are prohibited.
Packaging Wet or leaking Parcels, Parcels emitting odor of any kind
Perishables Foodstuff, Perishable Food Articles, Beverages requiring refrigeration or other environmental control
Plants Plants and Plant material, seeds
Pornography Foul or disgusting Material, Pornography and/or obscene Material, Any unsolicited Indecent Item or representation of any kind
Radioactive material Fissile material (Uranium 235, etc.) Radioactive waste material, Thorium or Uranium ores, etc. All material and samples that are classified as radioactive as in the International Civil Aviation Organization’s Technical Instructions are prohibited.
Remains Human and animal remains, Ashes
Sharp Tools/Weapons Scissors, Knives, Needles and Cartridges, Guns and Gun Accessories
Tobacco Products Cigarettes, Cigars, Electronic Cigarettes, Tobacco, etc.
Toxic and infectious substances Arsenic, Beryllium, Cyanide, Fluorine, Hydrogen Solenoid, Mercury, Mercury salts, Mustard gas, Nitrobenzene, Nitrogen dioxide, Pesticides, Poisons Rat poison, Ebola, Foot and mouth disease, Environmental, clinical and medical waste. Substances liable to cause death or injury if swallowed or inhaled, or by skin contact. All toxic substances are prohibited.
All toxic compressed gasses are prohibited (Chlorine, Fluorine, etc.)
All non-flammable compressed gasses are prohibited (Carbon dioxide, Neon, Helium, Nitrogen, Fire extinguishers, etc.)
General Unacceptable Commodities / All Origins Flammable Batteries, Standalone Batteries, Portable Batteries, Power Banks, Walkie Talkie, Drone Cameras, Lasers (as Laser Hair Removal or Laser Pens), Pets Supplements, Government issued documents (Including but not limited to Permanent Residence Cards, Green Cards, Work Permits, Passports, Driving Licenses, Health Cards, Correspondence from a respective country’s tax authority, e.g. Revenue Canada, Internal Revenue Service, HM Revenue and Customs) / Damaged/Broken phones of any kind (iPhone, Samsung etc.) Damaged / broken tablets of any kind, Hoverboard, Hookah & Hookah Accessories, Samsung Note 7, Any endangered species products (skin, hair etc.), All Liquids, Nail Polish, Spy Items.