Hi Christophe,
Sorry for the delay in responding you.
Custom chartYou can create custom chart by customizing the ChartSeriesRenderer class. In ChartSeriesRenderer class, you can provide the desired implementation details inside Render() method. This custom renderer can be attached to the ChartSeries using the below code snippet.
[C#]
series.Renderer = new MyChartRenderer(series);
Sample referencePlease refer the below sample that demonstrates how the ChartSeriesRenderer class can be customized and remove the SmallCircles on the top of Histogram and change the width and color of the NormalDistributionCurve.
http://websamples.syncfusion.com/samples/Chart.Windows/F43531/main.htmPlease let me know if you have any further questions.
Thank you for your interest in Syncfusion products.
Regards,
Jaya