Plate

Mass = 84184.05 gramsI started just like big rim where I made a sketch of half of the sketch. The bottom line is 85mm long, the bottom park is 100mm high. From one of the sides extend a line going 490mm high from the BOTTOM line, then start working on the top part where make a line 45 degrees from the main line and the one coming from the line and a straight line 20mm coming from that one. Constraint that my making the straight line and the main line 25mm wide. Make a line coming from that 20mm line at the end which is 45mm long coming down. From that line make a line going inward and leaving 30mm between its end point and the main line. Extrude that by using the revolve feature . Make a sketch on that inside circle and make a two line across the central line 20mm away from center line each. extrude that by 25mm and use the filler face and round the bottom corners by 10mm and the top right as well but the top left by 60mm. Use circular patterns after converting entities of the original one and so create a circular pattern of 9 going around and then extrude them all and you're done.