After some careful consideration, this may be a "Sklo Union" product.
With new research material having arrived, the significant phrase is "rucni lis, hutni tvarovano" hand-pressed, work-shop shaped. This has appeared with regard to several item descriptions.
In the case of this piece, it would have been formed initially by manual pressing in the mould, hence the regimented base pattern, then the top worked whilst still hot.
regards,
Marcus