Theres a huge range of Welsh Based invetions and discoveries to choose from such as

• David Thomas in 1837 invented a hot blast furnace process to make iron using anthracite coal in Ystradfera (Swansea Valley). transforming the iron-making process there and later in 1839 after re-locating to Pennsylvania where he became the "father" of the American steel industry with his invention
• Eddie Bowen pioneer of radar. Worked at 'Woomera Rocket Testing Base' in Australia. Invented artificial rain in the 1950s Born in Gendros, Swansea.
• David Brunt pioneer of modern meteorology. Head of Meteorological Office, secretary of Royal Society From Penfforddlas, Wales.
• Martha Hughes Cannon pioneer in women and children's medicine. The State of Utah's Health Department is named in her honour.

Born in Wales. Family from Llanddoged near Llanrst.

• John Chiplin Co-founder of 'GeneFormatics', leading biotech company, in 1999. Founded 'Newstar Music' 1995 and creative vehicle for the band, 'Vita Nuova'. Born in Cardiff.
• Archie Cochrane Founder of Cochrane Collaboration, Cochrane library, Cochrane reviews. UK Cochrane Centre in Oxford. Conducted much of his groundbreaking medical research in Wales. Cochrane archive is in Llandough Hospital, part of Cardiff University School of Medicine.Iian Cox Alan cox is a programmer heavily involved in the development of the Linux kernel since its early days (1991). He then became one of the main developers and maintainers of the whole kernel.
• Sir Clifford Darby Geographer and leader in promoting the relationships between geography and other subjects. Knighted in 1988. Born in Neath, South Wales.
• Donald Davies Proposed and developed packet switching an important part of the internet. Born in Wales
• Thomas Davies Along with his brother Walter he invented the 'Stepney Spare Wheel' used on almost all early motor cars. Born in Llanelli, South Wales
• John Ddu Founder of the new school of English mathematical scientists in 1500's. One of the greatest polymaths of all time. Born in Buallt, Radnor.
• Mr Dudson Invented the DUDSON Valve (the needle type) used to inflate sports balls everywhere. Lived in Abertridwr.
• Sir Chris Evans Britain's most colourful biotech entrepreneur. Born in Port Talbot.
• Bill Frost Welsh carpenter who patented the aeroplane in 1894 and took to the skies in a powered flying machine the following year, eight years before the Wright brothers attempt at Kitty Hawk. Born in Tenby.
• William Robert Grove Invented the Fuel Cell. Born in Swansea, 1811.
• John Houghton Distinguished meteorologist. Inspiration behind major international conferences on global warming (Rio, Kyoto, Buenos Aires). Born in Wales.
• David Hughes First transmission of radio waves. Inventor of the microphone and printing telegraph system. A musician and philosopher. Born Corwen, Wales.
• John Gwyn Jeffreys conchologist (someone who studies shells). He helped pioneer deep-sea dredging. He corresponded with Charles Darwin and was involved with a number of scientific associations. Born into a long-established Welsh family.
• Dyfrig Jones Theory of 'Planetary Radiation'. Born in Wales.[citation needed]
• Ernest Jones He introduced psychoanalysis into Britain and North America. Born in Llwchwy, South Wales
• Samuel Milton Jones Inventor, writer and Mayor of Toledo, Ohio, USA. Born in Carnarvonshire.
• Steve Jones Professor of genetics at the Galton Laboratory and University College, London. Born in Wales.
• William Jones A noted mathematician, published author and early naval navigator. First to use 'Pi' (1706) as a mathematical symbol. Born in Llanfihangel Tre'r Beirdd.
• Brian Josephson Nobel prize winning physicist; gave his name to 'Josephson Effects'. Born Cardiff.
• Bernard Knight Forensic pathologist, barrister and writer. Creator of the 'Crowner John' series, historic crime fiction. As a forensic pathologist, worked on the infamous Fred West case, recovering all twelve bodies. Born and spent most of his life in Cardiff.
• Francis Lewis Signatory of the US 'Declaration of Independence' as one of the representatives from New York. Born in Llandaff.
• Edward Lloyd Fellow of Jesus College Oxford. Keeper of the Ashmolean Museum and the foremost Celtic scholar of his time. Born Oswestry, 1660.
• Ronald M Lockley Famous naturalist and author. Best known for his life on Skokholm Island off Pembrokeshire 1927-1940 and at Orielton in 1950's early 1960s. Born in Cardiff.
• John Maddox Knighted for services to science. Author of several books. Born South Wales, 1925.
• Terence Matthews 'Mitel' and 'Newbridge' Networks founder. Billionaire. Born and raised in Wales.
• Gaynor Morgan Inventing and patenting the 'inco-stop'. Born in Bridgend.
• Kevin Morgan Groundbreaking work in the field of Pharmaceutical powder compacting. Born in Swansea.
• William Morgan (scientist) Inventor of the Vacuum Tube, Coolidge Tube, Britain's first actuary, founding father of modern actuarial science. The unknowingly discoverer of x-rays, a hundred and ten years before Roentgen! Born in Bridgend, 1750, died 1830
• Sir William H Preece William Henry Preece was an electrical engineer who was a major figure in the development and introduction of wireless telegraphy and the telephone in Great Britain. Born Feb 15 1834 in Bryn Helen.
• Dr Richard Pryce Was developer of the times tables for insurance scales. Born at Tynton Farm Llangeinor, South Wales
• Dr William Price re-introuduced cremation to Britain. Born Llantristant, South Wales
• Pryce Pryce-Jones Gave mail-order (catalogue) shopping to the world.(circa 1859) Born/lived in Newtown, Montgomeryshire (Powys).
• Robert Recorde Very influential physician and mathematician. Robert published some of the most important books of his era including the first English language book on Algebra which incidentally is where the equals symbol is first seen in use! He achieved high office too, being not only the king's physician but also the controller of the Royal Mint (which is now based in Llantrisant, South Wales). From Tenby, West Wales.
• Isaac Roberts He pioneered deep space photography at the end of the nineteenth century. Born in Groes near Denbigh in 1829.
• Richard Roberts Textile machinery, railway locomotives and other industrial inventions. Born Llanymynech, 1789.
• Earl Bertrand Russell Philosopher, mathematician and the Nobel Prize for Literature in 1950. Russell is one of the most highly regarded academics of the twentieth century. Helped perhaps by a great sense of humor, he popularized the mathematics and proposed many ground breaking theories. Born in Trelleck, Monmouthshire, South Wales.
• f Sir John M. Thomas Former Director of the Royal Institution. Previously held Chair of Physical Sciences at Cambridge. Before that Professor and Head of Chemistry Department at Aberystwyth. Member of the Bardic Circle of the National Eisteddfod.

Born in Wales of Welsh parentage.

• Sir Tudor Thomas World famous Welsh eye surgeon from Cardiff. He pioneered ophthalmic corneaplasty in the 1930s. Born in Ystradgynlais twenty-third May 1893.
• Brian Trubshaw Test Pilot for Concorde. From Llanelli, Wales.
• Alfred Russel Wallace Conferred with Darwin (and Darwin with him) regarding evolution of species and acknowledged as theory co -founder by Darwin in his 'On the Origin of Species'. Born South Wales.
• Evan Williams Distinguished physicist, discoverer of the Meson Particle. Born Cwmsychpant, Llandysul, Wales.
• Ernest Willows pioneering aviator. In 1910 became the first person to cross the English channel in airship. Born in Cardiff, 1896.

With thansk to my colleagues in Wikipedia for their help