Simplistic Stringification

IStringifier.cs

public interface IStringifier
{
    bool Matches(StringifyRequest request);
    string Stringify(StringifyRequest request);
}

Stringifier.cs

public class Stringifier
{
    private readonly IEnumerable<IStringifier> _stringifiers;

    public Stringifier(IEnumerable<IStringifier> stringifiers)
    {
        _stringifiers = stringifiers;
    }

    public string Stringify(StringifyRequest request)
    {
        var stringifier = _stringifiers.FirstOrDefault(s => s.Matches(request));
        if(stringifier == null) throw new InvalidOperationException("No stringifier found matching request");

        return stringifier.Stringify(request);
    }
}

StringifierDef.cs

public class StringifierDef
{
    public Type Type { get; set; }
    public IStringifier Value { get; set; }
}

StringifierModel.cs

public class StringifierModel
{
    private readonly IList<StringifierDef> _stringifiers = new List<StringifierDef>();

    public void AddStringifier(IStringifier stringifier)
    {
        _stringifiers.Add(new StringifierDef { Value = stringifier});
    }

    public void AddStringifier(Type stringifierType)
    {
        _stringifiers.Add(new StringifierDef { Type = stringifierType });
    }

    public IEnumerable<StringifierDef> Stringifiers { get { return _stringifiers; } }
}

StringifyRequest.cs

public class StringifyRequest
{
    public Type RequestType { get; set; }
    public object RawValue { get; set; }
}