The new MDF D-Seat from Euroshowers has a solid weight behind it (2720g) with robust metal soft closing hinges.  Now featuring the 2 button quick release for easy removal and cleaning.  Both top and bottom fittings are included so you can fit in minutes.

https://www.replacementtoiletseats.co.uk/ourshop/prod_6825742-Oak-MDF-D-SHAPED-Soft-Close-Toilet-Seat.html