RenderTools idea

public sealed class RenderTools
{
    private readonly IDictionary<Type, Func<object, Freezable>> _toolFactories = new Dictionary<Type, Func<object, Freezable>>();

    private readonly IDictionary<object, Freezable> _toolCache = new Dictionary<object, Freezable>();

    public void RegisterTool<TKey, TResult>(Func<TKey, TResult> toolFactory)
        where TResult : Freezable
    {
        this._toolFactories[typeof(TKey)] = new Func<object, Freezable>(
            p =>
            {
                var tool = toolFactory((TKey)p);
                tool.Freeze();
                return tool;
            });
    }

    public TResult GetTool<TResult>(object toolKey)
        where TResult : Freezable
    {
        Freezable result;

        if (!this._toolCache.TryGetValue(toolKey, out result))
        {
            result = this._toolFactories[toolKey.GetType()](toolKey);
            this._toolCache.Add(toolKey, result);
        }

        return (TResult)result;
    }
}